MPTET Varg 2 Science Mock Test - 5 - MPTET MCQ

The correct answer is Lipase.

Key Points

• Pancreatic juice contains a Lipase enzyme that breaks down emulsified fats.
• Lipase:
  • It is an enzyme that is found in pancreatic juice and is responsible for the breakdown of emulsified fat.
  • It is secreted by the Pancreas.
  • Lipases hydrolyze triglycerides (fats) into their component fatty acid and glycerol molecules.
  • Emulsification is the process of breaking down the large fat globules into smaller globules and making them water-soluble.​​​

Additional Information

• Pepsin:
  • Pepsin is the digestive enzyme that breaks down proteins.
  • The Gastric Glands secrete the enzyme Pepsin.
  • Gastric glands are found in the stomach.
  • They secrete enzymes like Pepsin, and Rennin which act upon the Proteins.
  • Glands in the mucous membrane which line the stomach make and store an inactive protein known as pepsinogen.
  • When pepsinogen is released into the stomach and mixed with gastric juice, it is converted into pepsin.
  • Pepsin partially degrades proteins into smaller units called peptides.
• Salivary amylase:
  • It is an enzyme present in human saliva which is produced by the salivary glands.
  • It helps in the process of digestion as it breaks down complex carbohydrates such as starch into simpler sugars like glucose and maltose.
• Trypsin:
  • It is secreted by the Pancreas.
  • It is a protein-digesting enzyme present in
    pancreatic juices secreted into the small intestine during a meal.
  • The pancreas secretes trypsin an inactive proenzyme called trypsinogen.

The correct answer is I, II, and III.

Key Points

• A natural object is located outside of the Earth's atmosphere, such as the Moon, the Sun, an asteroid, a planet, or a star.
•  Known collectively by astronomers as celestial objects, celestial bodies, astronomical objects, and astronomical bodies, they are the stuff that fills the empty space of the universe.
• Most of us are familiar with the stars, planets, and moons.
• But beyond these everyday celestial objects, lies an amazing collection of other wondrous sights.
• There are colorful nebulae, delicate star clusters, and massive galaxies.

Additional Information

• Stars:
  • A star is a form of a celestial object made up of a shining spheroid of plasma held together by its own gravity.
  • The nearest star to the Earth is the Sun. 
• Planets:
  •  In our solar system, we have eight planets; they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
  • The word planet is an ancient word that ties to history, astrology, science, mythology, and religion.
• Moon:
  • The Moon is a planetary-mass object with a discerned rocky body, making it a satellite earth under the geophysical delineations of the term and larger than all known dwarf globes of the Solar System.

The correct answer is Option 4 i.e.Locomotion.

Explanation:

• Vacuoles are membrane-bound intracellular organelle found in the cytoplasm of most plants, fungi and also some animal cells.
• The vacuoles are covered by a membrane called the tonoplast.
• Plant vacuoles contain not only water, sugars and salts, but also contain pigments and toxic molecules and also occupy upto 90% of the volume of the cell.
• They store substances that are not essentially useful for the cell (like water, sap, excretory product and other materials).
• The major function of vacuoles in plant cells is storage, maintaining cell turgor and rigidity, and also to protect cells during biotic stresses.
• Plant vacuoles also provides turgidity and rigidity to the cell.
• The fully filled vacuoles exert turgor pressure on the plant cell walls, which helps the plant cells maintain their shape and size and prevent wilting.
• Animal cells also have vacuole, but they are much more prominent in case of plant cells.
• The following types of vacuoles are found in different organisms 
• Contractile vacuole:
  • They play an important part in osmoregulation and excretion in Amoeba, etc.
  • It occurs mostly in protistan and algal cells that are found mainly in water.
• Food vacuole:
  • They occur in the cells of mainly protozoan protists.
  • The food vacuoles help in engulfing food particles.

Science involves the process of finding the truth by testing and investigating with evidence gathered from the surroundings. It is also referred to as an accumulated and systematized way of learning.

• The science curriculum refers to the overall subject matter of science to be taught in a specific period of time in a particular class. It includes all the co-curricular and recreational activities that are to be conducted in a science classroom.

Key Points 
Process validity:

• It requires that the curriculum should engage the learner in acquiring the methods and processes that lead to the generation of scientific knowledge.
• Process validity is an important criterion since it helps the student in "learning to learn" science.
• It nurtures the natural curiosity and creativity of the child in science.

Thus by all these references, we can say that Process validity is an important criterion since it helps the student in ‘learning to learn science. 

Important Points 
Content validity:

• It requires that the curriculum must convey significant and correct scientific information.
• Simplification of content, which is necessary for adapting the curriculum to the cognitive level of the learner must not be so trivialized as to convey something basically flawed or meaningless. 

Historical validity:

• It requires that the science curriculum be informed by a historical perspective.
• It should enable the learner to appreciate how the concepts of science evolve over time.
• It also helps the learner to view science as a social enterprise and to understand how social factors influence the development of science.

Cognitive validity: It requires that the content, process, language, and pedagogical practices of the curriculum are age-appropriate, and within the cognitive reach of the child. 

The correct answer is Vitamin K.

Important Points

Some important Vitamins:

Key Points

• There are three types of blood corpuscles namely:
  • Erythrocytes or red blood cells,
  • Leucocytes or White blood cells.
  • Thrombocytes or Blood platelets.
• Blood Platelets or Thrombocytes:
  • They are only found in the blood of human beings & mammals in which nuclei are absent.
  • These are composed of the cytoplasm of a larger nuclear cell of bone marrow.
  • Its average life span is 7 days.
  • Platelets are produced from very large bone marrow cells called Megakaryocytes.
  • When the blood capillaries are cut, then blood platelets come at the point of damage and starts to accumulate by secreting a special type of chemical which helps in blood clotting.
• Blood Clotting:
  • It is the conversion of normal viscous blood fluid into a jelly-like mass within 3-10 minutes after its exposure to air.
  •  The mechanism of blood clotting comprises of three steps which are the following:
    • Stage I: The thromboplastin is released from the injured tissue.
      • It changes into the prothrombinase enzyme.
    • Stage II: Prothrombinase inactivates Heparin & catalyse the breakdown of prothrombin into thrombin.
    • Stage III: Active thrombin converts blood soluble fibrinogen into fibrin.
  • The thrombin acts as an enzyme to convert soluble fibrinogen of blood into insoluble fibrin threads in which RBCs get trapped.
    • As a result, the clot is formed at the site of injury.

Additional Information

• Heparin is the anti-clotting substance that exists in blood & prevents it from clotting inside blood vessels by prohibiting catalytic activities of prothrombin.
  • Basophils and mast cells produce heparin in all mammals.
• Disorders with low platelet counts are called Thrombocytopenia.

Concept:

IUPAC nomenclature:

• A systematic method of naming organic compounds.
• Naming is based on their structures.
• It is devised by the International Union of Pure and Applied chemistry.
• Many rules are followed while naming the compounds and it is different for different functional groups.
• The rules are known as < />IUPAC rules.

Explanation:

• As per the IUPAC naming rules, first, the longest chain should be found out.
• The numbering should be done in a way that the highest functional group gets the lowest number.
• The sequence is given as follows:

• Hence number from the right side, COOH will get number 1, and C=O will get number 4.
• The total carbon in the longest chain is 5.
• There is a carboxylic acid group hence pentanoic acid and at number 4, there is an oxo group attached, hence 4 – oxopentanoic acid. 

The correct answer is Cornea.

• The outer surface of the cornea is responsible for most of the refraction of light rays entering our eyes.
• The cornea is a thin membrane through which the light rays enter our eyes.
• It forms the transparent bulge on the front surface of the eyeball.
• The retina is one of the three layers of the eye, where image formation takes place. The other two are choroid and sclera. It is light-sensitive in nature.
• Iris is a dark muscular diaphragm, present behind the cornea, that controls the size of the pupil.
• The eye lens is biconvex in nature and helps in the adjustment of the focal length so that the object focuses on the retina. It forms an inverted real image of an object on the retina.
• The structure of the human eye is shown below:

The correct answer is White surface reflects more heat energy and absorbs less heat energy.

Key Points

• A white surface reflects more heat energy and absorbs less heat energy this is the reason the top and outer surfaces of the house are painted white.
• White color is a poor emitter of heat.
• Hence, white-colored clothes are preferred in summer.

Additional Information

• The black color is a good absorber and a better emitter of heat.
• Hence, the inner side of the solar cooker is painted black
• Transfer of it takes place in three ways conduction, convection, and radiation.

Concept:

Acid rain - 

• When sulphur and nitrogen particles emitted from various means like manufacturing processes and vehicles, mixed with tiny droplets of rain cause precipitation of the acid and come to the earth's surface with the rain. 
• This type of rain is highly acidic in nature.
• It harms the environment, especially agriculture, animals, aquatic life and plants.
• It destroys the historical buildings and marbles.

Tropospheric pollution - The presence of gaseous or solid unwanted particles like oxides of sulphur and nitrogen, and particulate matter in the troposphere of the environment causing Tropospheric pollution.

Ozone depletion - 

• Ozone is a protecting layer present in the Stratosphere of the environment.
• It protects us from harmful UV rays coming from the sun.
• But due to some natural or human activities, it becomes thin day by day or gets depleted which is known as the depletion of othe zone layer.
• Deletion of ozone is a serious issue.
• The main reason for the depletion of ozone is CFCs.

Smog - 

• It is a type of air pollution.
• It is not healthy for human as well as plant lives.
• It causes environmental pollution.

Explanation:

• Tropospheric pollution: In the presence of pollutant or water vapours present in the environment, SO₂ converts into SO₃ which form the major pollutant of tropospheric pollution.

           2SO₂ + O₂ → 2SO₃

• In the spring season, sunlight breaks HOCl and Cl2 to give chlorine radicals. When these radicals come in contact with the ozone layer, they start destroying it. The chemical reaction for the following is -
• 
• A high level of sulphur causes acid rain which reacts with calcium carbonate present in marbles and CO₂ is released as a product of the reaction. This causes discolouring and disfiguring of marbles. A recent example is the discolouring of the Taj Mahal.

          CaCO₃ + H₂SO₄  →→ CaSO₄ + H₂O + CO₂

• A chain reaction occurs from the interaction of NO with sunlight in which NO is converted to NO2 which absorbs energy from sunlight and breaks into NO and O, which causes photochemical smog. Smog is very dangerous to the environment and causes environmental pollution. It is the main reason for low visibility.

So, match them accordingly we get, (a) - (iv), (b) - (iii), (c) - (i), (d) - (ii).

Hence, the correct answer is option 4.

The correct answer is ​1 and 2 only.

Key Points

• Hot springs are heated by geothermal heat—heat from the Earth's interior.
  • In volcanic areas, water may come into contact with very hot rock heated by magma. Hot springs in active volcanic zones may produce superheated water, so hot that immersion can result in injury or death.
  • In non-volcanic areas, the temperature of rocks within the Earth also increases with depth, this temperature increase is known as the Geothermal Gradient.
  • If water percolates deeply enough into the crust, it comes into contact with hot rocks and can circulate to the surface to form hot springs.
  • Low-temperature geothermal resources occur in two types of geothermal systems: hydrothermal convection and conduction dominated.
  • In areas with no volcanic activity, this heat flows through the crust by a slow process of thermal conduction, but in volcanic areas, the heat is carried to the surface more rapidly by bodies of magma through convection. Hence, Option 4 is the correct answer.

Additional Information

• Conduction: The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction. In solids, generally, the heat is transferred by the process of conduction.
• Convection: The process by which heat is transferred by the movement of a heated fluid such as air or water is known as convection. Natural convection results from the tendency of most fluids to expand when heated—i.e., to become less dense and to rise as a result of the increased buoyancy.
• Radiation is energy that comes from a source and travels through space at the speed of light. This energy has an electric field and a magnetic field associated with it, and has wave-like properties. 

The teaching of science must be done to promote divergent thinking, scientific attitude, and to make them encourage enough to individually discover and explore their world to learn more in a realistic environment, by real and direct experiences.

Important Points

• The teaching method is a way to put theory into practice. The process of interpreting the world of knowledge to a pupil's mind is called the method of teaching.
• It helps a teacher to understand "what to teach", "how to teach", "how to approach it". It includes both strategies and techniques of teaching and involves the choice of what is to be taught.

Key Points

Lecture method:

• It is one of the oldest methods of teaching which is based on the principle of idealism.
• It is a teacher and information-centered approach which only aims at giving knowledge to the students by theoretical approach.
• In this method, the stress is given to make the students gain their knowledge by abstractions which is effective to some extent in higher classes.
• It is not good for average and below-average students and starts from abstract. It is used to provide an overview of larger content or subject matter.
• The teacher becomes an orator rather than a teacher and students remain inactive as the teacher explains and the students passively observe and listen to their teacher.
• This method does not cater to the problem of individual differences and gives short-term learnings i.e., whether a child is a slow-learner or gifted, the teacher will teach all equally without giving them proper opportunities to learn at their natural pace.

Hence, it could be concluded that 'It is good for average and below average students and goes from concrete to abstract' is not true regarding lecture method while teaching science.

The correct answer is Lymphocytes.

Explanation:

• B cells and T cells are the main types of lymphocytes.
• B cells work chiefly by secreting substances called antibodies into the body’s fluids. 
• Antibodies ambush antigens circulating the bloodstream. 
• They are powerless, however, to penetrate cells. The job of attacking target cells—either cells that have been infected by viruses or cells that have been distorted by cancer—is left to T cells or other immune cells.
• Each B cell is programmed to make one specific antibody. For example, one B cell will make an antibody that blocks a virus that causes the common cold, while another produces an antibody that attacks a bacterium that causes pneumonia.
• When a B cell encounters its triggering antigen, it gives rise to many large cells known as plasma cells. 
• Every plasma cell is essentially a factory for producing an antibody. 
• Each of the plasma cells descended from a given B cell manufactures millions of identical antibody molecules and pours them into the bloodstream. 
• An antigen matches an antibody much as a key matches a lock. Some match exactly; others fit more like a skeleton key. 
• But whenever antigen and antibody interlock, the antibody marks the antigen for destruction.

• The isotopes of Sulphur and Carbon are given incorrectly.
• Isotopes of Carbon : ¹²C₆ , ¹³C₆ , ¹⁴C₆
• Isotopes of Sulphur : ³²S₁₆ , ³³S₁₆, ³⁴S₁₆, ³⁵S₁₆
• Atoms of the same element that contain same number of electron but different number of neutrons are termed as Isotopes. Thus, isotopes have same Atomic Number but different Mass Number.

The correct answer is Dendrite.

Important Points

• Dendrites are projections of a neuron (nerve cell) that receive signals (information) from other neurons.
• The transfer of information from one neuron to another is achieved through chemical signals and electric impulses, that is, electrochemical signals.
• The information transfer is usually received at the dendrites through chemical signals, then it travels to the cell body (soma), continues along the neuronal axon as electric impulses, and it is finally transferred onto the next neuron at the synapse, which is the place where the two neurons exchange information through chemical signals.
• At the synapse meet the end of one neuron and the beginning—the dendrites—of the other.

Key Points

• The functions of dendrites are to receive signals from other neurons, to process these signals, and to transfer the information to the soma of the neuron.
• The dendrites resemble the branches of a tree in the sense that they extend from the soma or body of the neuron and open up into gradually smaller projections.
• At the end of these projections are the synapses, which is where the information transfer occurs.
• More specifically, synapses are the site where two neurons exchange signals: the upstream or presynaptic neuron releases neurotransmitters (usually at the end of the neuron, also called axonal terminal), and the downstream or post-synaptic neuron detects them (usually in the dendrites).
• This figure shows the synapse of a pre-synaptic neuron (A) and a post-synaptic neuron (B).

Additional Information

Axon :

• Axons are in effect the primary transmission lines of the nervous system, and as bundles, they help make up nerves.
• Individual axons are microscopic in diameter - typically about one micrometer across - but may extend to macroscopic lengths.
• The longest axons in the human body, for example, are those of the sciatic nerve, which runs from the base of the spine to the big toe of each foot.
• These single-cell fibers may extend a meter or even longer.

Mitochondria :

• Mitochondria are often referred to as the powerhouses of the cell.
• They help turn the energy we take from food into energy that the cell can use. But, there is more to mitochondria than energy production.
• Present in nearly all types of human cells, mitochondria are vital to our survival.
• They generate the majority of our adenosine triphosphate (ATP), the energy currency of the cell.
• Mitochondria are also involved in other tasks, such as signaling between cells and cell death, otherwise known as apoptosis.

Nerve Ending :

• Nerve endings are the millions of points on the surface of our body and inside it which send messages to our brain when we feel sensations such as heat, cold, and pain.

Key Points

• Fluoride or fluorine deficiency is the disorder that may cause increased dental carries is the breakdown of dental tissues.
• This breakdown is by the acidic products released by the bacterial fermentation of dietary carbohydrates.

Methemoglobinemia:

• Methemoglobinemia is a blood condition where cells receive insufficient oxygen.
• There are two types of methemoglobinemia: acquired and congenital.
• Excess nitrates is harmful to infants and causes methemoglobinemia.
• It is also called Blue baby disease.​

Additional Information

• Pernicious anemia is one cause of vitamin B₁₂ deficiency.
• Xeropthalmia is a disease that causes dry eyes and is caused due to deficiency of vitamin A.
• Osteomalacia is a disease where bones become brittle and soft.​

Therefore, the disease caused by excessive nitrates (Above 550 nm) in drinking water is Methemoglobimenia.

The correct answer is 20.

• Here given, Z = 17 = Number of protons, Mass number = 37.
  We know, Mass number = Number of protons + Number of neutrons.
  So, Neutrons present in nucleus = Mass number - Number of protons (Z) = 37 - 17 = 20.

Important Points

• Atomic number (Z) is the number of protons present in the nucleus which is equal to the number of electrons present in the atom.
• The mass number is the sum of the number of protons and neutrons which is indicated with the letter A.

Additional Information

• Tritium is the isotope of Hydrogen. It contains 1 proton and 2 neutrons.
• The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance.
• The "magic numbers" for atoms are numbers of protons and/or neutrons that confer nuclear stability.
• Gamma radiation leaves both the atomic number and mass number unchanged.

Ultrafiltration-

• Blood is filtered through this glomerulus and the filtrate gets accumulated in the Bowman capsule and then it is propelled towards the tubule, this process is known as Filtration.
• As initially Renal arteriole enters into the Bowman’s capsule of a nephron and forms a mesh-like network, in the same way, the network gets collected to expel unfiltered blood out of nephron through another blood vessel. This blood vessel itself surrounds the nephron.
• The exchange of various substances takes place between the above Two filtrates; one which is filtered by the glomerulus and accumulated in tubules and another one is unfiltered blood which is present in the blood vessels surrounding the nephron.

Reabsorption-

• Various substances which are required to the body are absorbed again from the blood by the nephron, it is known as “Reabsorption’. Reabsorption takes place in two-part

1. PCT - absorption of Glucose and amino acid
2. Loop of Henle -

• Descending Limb - absorption of water
• Ascending limb  - absorption of sodium

Secretion-

• The process in which the waste products (which are not required by our body) are secreted back into Nephron via blood is known as “Secretion’.
• Example - Urea, Uric Acid.
• This process takes place in DCT.

Excretion-

Science (from the Latin word scientia, meaning knowledge) is the activity and application of knowledge and understanding of the social and natural world around us followed by systematic approach based on evidence.

• Science includes study of the physical and biological world around us through several approaches like observation, experimenting, inference etc. while technology involves application of that scientific knowledge for practical purposes.

Key Points

Nature of science :

• Science is truly international enterprise.
• Science is a particular way of looking at nature.
• Scientific method is used to prove or validate scientific ideas.
• Science and technology are not the same but they have an impact on each other.
• Science is long lasting yet tentative and objective also. Science is not static, it can change hence tentative.
• Empirical evidence leads to scientific knowledge. Science is not just a collection of facts, it requires empirical evidence also.
• Science is a process of inquiry. Science is a process of asking questions and finding answers, then creating divergent generalization.
• Science promotes skepticism which is a matter of questioning, seeking, inquiring the doubt. While performing any scientific research and inquiry skepticism helps scientists to remain objective. 
• Science is an interdisciplinary subject of knowledge which means different fields of study. For example, if you read a science fiction novel, you are covering two disciplines here, literature and science.

Hence, it could be concluded that Science does not promote skepticism is false about nature of science.

Concept:

• The plant kingdom includes algae, bryophytes, pteridophytes, gymnosperms, and angiosperms.
• In pteridophytes, the main plant is a sporophyte differentiated into true roots, stems, and leaves.
• These organs possess well-differentiated vascular tissues. 

Explanation:

• Bryophytes are plants that can live in soil but depend on water for sexual reproduction.
• The plant body of bryophytes is more differentiated than that of algae.
• It is thallus-like, prostrate, or erect and attached to the substratum by rhizoids.
• They possess root-like, leaf-like, and stem-like structures.
• Bryophytes have embryos but lack vascular tissue.​​

Additional Information 

• The division Cyanophyta is commonly known as blue-green algae.
• Pteridophytes are considered to be the first plant to be evolved on the land.
• The presence of vascular tissue is one of the characteristics of tracheophytes.
• All grass, ferns, and shrubs are examples of tracheophytes.​

Therefore, Bryophytes are a group of plants that have embryos but no vascular tissue.

The correct answer is Hydrogen ions.

Key Points

• Acids and Bases exhibit their conducting property only if they are in an aqueous solution because they could completely ionize in water
• As per Arrhenius' concept, acids are those that produce the hydrogen ion(H+) when dissolved in water
• Bases produce the hydroxide ion(OH-) when dissolved in water
• These ions, when in water, act as charge carriers and can hence conduct electricity.
• The pH level is a measure of the number of Hydrogen ions in a solution.
• The lower the solution or compound on the pH scale, the higher will be the concentration of hydrogen ions.

Concept:

Electronic configuration:

• The arrangement of electrons in the electronic levels of an atom is called its electronic configuration.
• The electrons are arranged according to their energies and space availability.
• There are a few sets of rules which we follow while arranging the electrons in an atom.

They are-

• Aufbau principle-
  • ​It states that the atomic orbitals which have lower energies are filled first.
  • Then the electron goes to occupy the higher atomic energy levels.
  • This ruled is followed to write the electronic configuration of atoms in their ground state.
  • When in the excited state, the electrons might vacant the lower energy state and move on to a higher energy state.
  • The order in which atomic orbitals are filled are: 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p.
  • The order follows that the lower (n + l) value of atomic orbital will have lower energy, where n = principal quantum number and l = azimuthal quantum number.
• Pauli's exclusion principle:
  • ​An electron is characterized by four quantum numbers n, m, l, and s.
  • Pauli's exclusion principle states that every electron must have its unique set of these four quantum numbers.
  • No two electrons can have the same set of quantum numbers.
  • Simplifying, we may say that an orbital can contain a maximum of two electrons and the two electrons should have opposite spins ( + ½, - ½ ).
• Hund's rule of maximum spin multiplicity:
  • ​While filling up the orbitals of the same energy, or degeneracy, electrons will first singly occupy the subshell.
  • After each subshell has been singly occupied, electron pairing will start.
  • This rule thus implies that maximum spin should be maintained while filling up electrons in a subshell.
  • The maximum spin state involves maximum exchange energy and yields a more stable state.

Explanation:

​Element Copper(Cu):

• Element Cu has an atomic number 29.
• The electronic configuration should be: 1s2 2s2 2p6 3s2 3p6 4s2 3d9.
• However, the actual electronic configuration is 1s2 2s2 2p6 3s2 3p6 4s1 3d10 or [Ar] 3d104s1.
• This is because the half-filled and fully filled configurations (d5 d10 f7 f14) have lower energy or more stability.
• Thus, in order to become stable, the 5s electrons go into 4d orbitals so that 4d orbitals have a fully filled configuration.
• The electron can easily make the transition from 4s to higher energy 3d orbital.
• This is feasible because of the low energy difference between the 4s and 3d orbitals.

Hence, electronic configuration of copper [Z = 29] is [Ar] 3d104s1.

Concept:

• Mass by mass solution is given as 

• The solute is the substance that is dissolved in the solution. 
• The solution is basically solute + solvent. 
• For example in the sugar solution of water, sugar is solute, water is solvent, and their homogenous mixture formed is the solution. 

Calculation:

Given, mass of sugar = 30 gm

mass of water = x (Let)

given mass by mass solution is 10 % or 10 / 100

So, we can say that the mass by mass solution as

⇒ 300 = 30 + x

⇒ x = 270 

So, the correct option is 270 gm.

All the above statements are correct.

• Molecular mass
  • Molecular mass of a substance is defined as the sum of the atomic masses of all the atoms present in a molecule of a substance.
  • Therefore the relative mass of a molecule is expressed as atomic mass units (amu).
  • Molecular mass of methane, (CH₄) = (12.011 u) + 4 (1.008 u) = 16.043 u
• Formula Mass
  • The formula mass of a molecule (also known as formula weight) is the sum of the atomic masses of the atoms in the empirical formula of the compound. It is for ionic compounds.
  • Some substances, such as Sodium Chloride do not contain discrete molecules as their constituent units.
  • In such compounds, positive (sodium ion) and negative (chloride ion) entities are arranged in a three-dimensional structure
  • For example : Formula mass of sodium chloride is atomic mass of sodium + atomic mass of chlorine = 23.0 u + 35.5 u = 58.5 u

(Reference: 11th NCERT Textbook page no. 14)​

The correct answer is Atoms combine in the ratio of small real numbers to form compounds.

Key Points

• Postulates of Dalton's Atomic Theory:
  • All matter consists of indivisible particles called atoms.
  • Although identical in mass and shape, atoms of the same element are distinct from those of other elements.
  • Atoms cannot be created or destroyed.
  • Compound atoms can be created by the combination of atoms from various elements in set, straightforward, whole number ratios.
  • A single element's atoms can mix in several ways to create two or more compounds.
  • The smallest piece of matter that can participate in a chemical reaction is the atom.​

Additional Information

•  Drawbacks of Dalton's Atomic Theory:
  • The fact that an atom may be further divided into protons, neutrons, and electrons disproves the idea that it is indivisible.
  • Dalton asserts that the atoms of the same element are identical in every way.
  • However, the masses and densities of various element's atoms differ.
  • Isotopes are these atoms with various masses.
  • Dalton also asserted that atoms of various elements differ from one another in every way.
  • In some instances, it has been shown that this is incorrect.
  • The atomic masses of calcium and argon are both 40 amu.
  • Isobars are the name for these atoms.
  • According to Dalton, compounds are created when atoms from several elements mix in straightforward whole number ratios.
  • Complex chemical molecules like sugar do not show this (C12H22O11).

Concept -

Tyndall Effect : 

• The Tyndall effect is the phenomenon whereby the particles in a colloid scatter light beams aimed at them.
• All colloidal fluids exhibit this effect.
• As a result, it can be used to determine if a solution is a colloid or not. 
• The intensity of scattered light is determined by the density of colloidal particles as well as the incisive frequency.
• When a beam of light travels through a colloid, the colloidal particles in the solution prevent the beam from passing through fully.
• The light is scattered when colloidal particles collide (it deviates from its normal trajectory, which is a straight line).
• The course of the light beam is visible as a result of this dispersion.
• John Tyndall, an Irish physicist, was the first to discover (and name) the Tyndall effect.
• Particles that create the Tyndall effect can have sizes ranging from 40 to 900 nanometers (1 nanometer = 10-9 metres).
• The wavelength of visible light, on the other hand, extends from 400 to 750 nanometers.

Examples of the Tyndall effect : 

1. Milk

• Milk is a colloid that contains fat and protein globules.
• A beam of light is scattered when it is directed at a glass of milk.
• The mixture of different sized particles altogether causes this dispersion. 

2. Fog 

• The path of light becomes evident when a torch is turned on in a foggy atmosphere.
• There are droplets present in fog which are quite big.
• These droplets cause light to scatter hence causing the Tyndall effect. 

​3. Sky 

• The sky's colour is caused by sunlight scattering around particles in the high atmosphere.
• The Earth's atmosphere contains gases and particles that scatter sunlight in all directions.
• Because blue light travels in shorter, smaller wavelengths, it scatters more than other colours.
• The Tyndall effect causes this scattering and thus, the sky colour's blue. 

​4. Smog 

• Smog is a colloid called aerosol, which comprises solid particles in a gas (air).
• These solid particles disperse a beam of light, which exhibits the Tyndall effect.

5. Gold Sol 

• A multimolecular sol is a gold sol that has particles of varying sizes made up of several gold atoms.
• As gold sol is thus a colloid, it exhibits the Tyndall effect.

Explanation -

• Tyndall effect is shown by colloidal solutions.
• This effect causes the dispersion of light by the greater sized particles.
• Hence, the light is visible in these colloidal solutions.
• Out of the given four options -
  • Smoke, the blue colour of the sky, gold sol are colloidal solutions and exhibit the Tyndall effect.
  • Glucose solution is a homogenous solution and not a colloidal solution, in which the solute particles have sizes of 0.1 nm to 1 nm or molecular dimensions.

Hence, glucose solution will not exhibit the Tyndall effect. 

The correct answer to this question is - glucose solution. 

The correct answer is the Biogeochemical Cycle.

Explanation:

• The movement of nutrient elements through various components (abiotic + biotic) of an ecosystem is called nutrient cycling or biogeochemical cycle.
• The total amount of nutrients like carbon, Phosphorus, calcium, etc., present in the soil at any time is called the standing state.
• Biogeochemical cycles are basically divided into two types:
• Gaseous cycles – Includes Carbon, Oxygen, Nitrogen, Water cycle.
• Sedimentary cycles – Includes Sulphur, Phosphorus cycle.
• ​Water cycle:
  • Water evaporates, cools, condenses, and falls back to earth as rain from the various bodies of water.
  • This biogeochemical cycle is responsible for maintaining the weather conditions.
• Carbon cycle: 
  • It is one of the biogeochemical cycles that exchanges carbon between the biosphere, geosphere, hydrosphere, atmosphere, and pedosphere.
  • Carbon is returned to the atmosphere as CO₂ by animals and plants through respiration and the activities of decomposers.
• Oxygen cycle: 
  • This biogeochemical cycle occurs in the atmosphere, lithosphere, and biosphere. Oxygen is an abundant element on our Earth.
  • It is found in the atmosphere in the elemental form to the extent of 21%.
• Nitrogen cycle: 
  • It is the biogeochemical cycle that converts nitrogen into various forms and circulates it through the atmosphere and various ecosystems such as terrestrial and marine ecosystems.
• Sulphur cycle:
  • This biogeochemical cycle moves through rocks, bodies of water, and living systems. Weathering of rocks releases sulphur into the atmosphere, where it is converted into sulphates.
  • Microorganisms and plants absorb these sulphates and convert them to organic forms.
• Phosphorus cycle:
  • Phosphorus moves through the hydrosphere, lithosphere, and biosphere in this biogeochemical cycle. The weathering of rocks extracts phosphorus. Phosphorus is washed away in the soil and water bodies as a result of rain and erosion.

Additional Information

• Importance of Biogeochemical Cycles
  • These cycles demonstrate how the energy is utilised. These cycles transport the elements required for life to survive throughout the ecosystem. 
  • They are essential because they recycle and store elements, as well as regulate vital elements through physical facets. 
  • These cycles represent the interaction of living and non-living things in ecosystems and enable the continuous survival of ecosystems.

Concept:

The heat of Hydrogenation:

• The order of stabilities of an alkene can be justified from their heats of hydrogenation values.
• When hydrogen is added to an alkene, an alkane is formed with the evolution of heat energy.
• Heat is produced in this reaction. The heat evolved is called the heat of hydrogenation.
• The heat of hydrogenation of an alkene can be measured experimentally.
• Most alkenes have heats of hydrogenation near -125.4 kJ per mol.
• The heat of hydrogenation differs in individual alkenes by 8 kJ/mol.

Explanation:

​Stability of alkenes:

• The more the heat of hydrogenation, the less stable is the alkene.
• The stability of alkene also depends on the alkyl substitution.
• The greater the alkyl substitution, the greater is the stability of an alkene.
• The higher stability of alkenes can be attributed to the higher degree of hyperconjugation of the more substituted alkenes.
• The cis alkenes are also less stable than the trans alkenes because the bulkier groups present in close proximity cause more steric strain.
• The alkanes given H3C CH = C(CH3) CH2 CH3,  H3C CH = CH - CH (CH3)2, H2C = C (CH3) CH2 CH2 CH3 and (H3C)2 C = C (CH3)2 have different degrees of substitution about the double bond.
• The most substituted alkenes among the following are (H3C)2 C = C (CH3)2, and thus it will have the highest degree of hyperconjugation and stability.

Hence, (H3C)2 C = C (CH3)2 is the most stable alkene.

The correct answer is 3.75.

Key Points

Electric Power - The rate of doing work is called power. This is also the rate of consumption of energy. The rate at which electric energy is dissipated or consumed in an electric circuit is also termed as electric power.

• The power P is given by P = VI Or P = I²R = V² / R.
• The S.I. Unit of electric power is the watt (W). It is the power consumed by a device that carries 1 A of current when operated at a potential difference of 1 V. Thus, 1 W = 1 Volt × 1 ampere = 1 V A.
• The unit 'watt' is very small. Therefore, in actual practice, we use a much larger unit called 'kilowatt'. it is equal to 1000 watts.
• Electric energy is the product of power and time, the unit of electric energy is 'watt-hour' ( W h).
•   1 watt-hour is the energy consumed when 1 watt of power is used for 1 hour. The commercial unit of electric energy is kilowatt-hour (KW h), commonly known as Units.
• 1 KW h = 1000 watts × 3600 seconds = 3.6 × 10⁶ watt second = 3.6 × 10⁶ joule (J).

CONCEPT:   Electric energy = Power × Time 

CALCULATION: ^​

• power = 1250 watt = 1.25 kw,
• time = 3 hours ​
• electric energy = ?

​BY FORMULA: 

Electric energy = power × time 

Electric energy = 1.25 kw × 3 h 

Electric energy = 3.75 kw h or  3.75 units

So, the electric energy consumption per day by an electric iron is 3.75 units.

Correct answer: 2)

Concept:

Law of Conservation of Mass: Law of conservation of mass states that the mass can neither be created nor destroyed but is transformed from one form to another.

That is during a combustion reaction, the total mass of the reactant should be equal to the total mass of the product.

Explanation:

For the given chemical reaction in option 1, 

2Mg(s) + O2(g) → 2MgO(s)

Mass of Mg= 24 

Mass of O=16 

Mass of reactant side; 2Mg + O2

=(2 mol x24  +2 mol  x16 )

= 80 gram

Mass of product side;2 MgO

2 mol (24 +16)

=80 gram

For the given chemical reaction in option 2 , 

C3H8(g) + O2(g) → CO2(g) + H2O(g)

Mass of C= 12 

Mass of H=1 

Mass of O=16 

Mass of reactant side; C3H8(g) + O2(g)

=(3 mol x12  +8 x1 ) +(2 mol x16 )

=76 gram

Mass of product side;CO2(g) + H2O(g)

(1mol x12 +2 mol x16 )+(2 mol x1 +1 mol x16 )

=62 gram

For the given chemical reaction in option 3 , 

P4(s) + 5O2(g) → P4O10(s)

Mass of P= 31 

Mass of O=16 

Mass of reactant side; P4(s) + 5O2(g)

=(4 mol x31 ) +(10 mol x16 )

=284 gram

Mass of product side; P4O10(s)

(4 mol x31 +10 mol x16 )

=284 gram

For the given chemical reaction in option 4 , 

CH4(g) + 2O2(g) → CO2(g) + 2H2O (g)

Mass of C= 12 

Mass of H=1 

Mass of O=16 

Mass of reactant side; CH4(g) + 2O2(g)

=(1 mol x12  +4 mol x1 ) +(4 mol x16 )

=80 gram

Mass of product side;CO2(g) + 2H2O(g)

(1 mol x 12 +2 mol x16 )+2 (2 mol x1 +1 mol x16 )

=80 gram

Conclusion:

Hence, from the above calculation, it is clear that the total mass reactants in the following reaction C3H8(g) + O2(g) → CO2(g) + H2O(g) is not equal to the total mass of the product as it does not follows the law of conservation of mass.

Additional Information 

Elements having same atomic numbers but a different mass number are called Isotopes.

• Isotopes have different physical properties and similar chemical properties.

• They are the atoms of the same element having the same numbers of protons but different numbers of neutrons.
• They have same chemical properties due to the same electronic configuration but different physical properties.