The magnification of plane mirror is:
The magnification of plane mirror is 1 since the size of the image is the same as the size of the object. The distance of the image from the mirror is the same as the distance of the object from the mirror.
Your school lab has one large window. To find the focal length of a concave mirror using one of the walls as the screen, the experiment may be performed:
The experiment may be performed on the same wall as the window to obtain a sharp image since a concave mirror mostly forms images on the same side as that of the object. The object and the image are on the same side of the concave mirror, except when the object is placed between the pole and the focus.
Which of the following is/are good conductor(s) of electricity?
Metals are electropositive in nature and are therefore, good conductors of electricity. Quartz is a chemical compound consisting of one part silicon and two parts oxygen (SiO2). It is the most abundant mineral found in Earth's surface. Its unique properties make it one of the most useful natural substances. It has electrical properties and heat resistance that make it valuable in electronic products. Mica has superior electrical properties as an insulator. Rubber is also an insulator.
Manganin is an alloy of:
Manganin is an alloy of copper, manganese and nickel. It typically contains 86% copper, 12% manganese, and 2% nickel. It was first developed by Edward Weston in 1892 improving upon his Constantan. Manganin wire is used in the manufacture of resistors.
The far point of a healthy person is
The far point is infinity for normal eye. It is the farthest point upto which the eye can see object clearly.
Match the following with the correct response.
(4) Crystalline lens
(A) Outer bulging part of the eye from the front
(B) A natural double convex lens
(C) A dark muscular diaphragm that controls the size of the pupil
(D) Outermost covering containing internal parts
Scleroid: It is the outermost part of the eye. It protects the inner delicate parts of the eye.
Cornea: It is a thin membrane through which light enters. It forms the transparent bulge on the front of eyeball.
Iris: It is a dark muscular diaphragm that controls the size of pupil. It is behind the cornea and gives colour to the eye.
Crystalline eye lens: It is composed of a fibrous, jelly like material. This is double convex lens that converges light at retina
A ray of light travelling in air fall obliquely on the surface of a calm pond. It will-
When ray of light enters from a rarer medium (air) into a denser medium (water), it bends towards normal at the point of incidence.
Which of the following is a vector quantity
Momentum is a vector quantity. A vector quantity possesses both a magnitude and direction. Since mass is a scalar quantity and velocity is a vector quantity, we can derive that momentum must therefore be a vector quantity as the product of a vector with a scalar is a vector.
Match the following with correct response.
(2) Area around a magnet is which It's attracting or repelling power can be experienced
(3) Device which converts mechanical energy into electrical energy
(4) Andre Marie Ampere
(A) Works on electromagnetic principle
1- A because dynamo works on the principle of electromagnetism.
2-C, because the area around which a magnet's magnetism is experienced is called magnetic field or magnetism.
3-B, the device which converts mechanical energy into electrical energy is electric generator.
4-D Andre Marie ampere discovered current and after her name i.e ampere is given.
Which of the following organs in the human body where the magnetic field produced is significant?
The human body is an electromagnetic organism. In human body, small electric currents travels along the nerve cells due to ions, same way as electricity flows through an electric wire. This current produces a very weak magnetic field in the human body. Heart and brain are the two main organs in the human body where this magnetic field is quite significant.
Match the following with correct response.
(1) Appliances with exposed metal parts always need
(2) The unidirectional current flow in the circuit
(3) The current which changes its direction at regular intervals
(4) Device that makes use of the fact that magnetism in presence of electricity produces motion
(B) Electric Motor
(D) Three pin plug
‘An electric current always produces a magnetic field’ , The above statement is
Which of the following is the conventional sources of energy?
All given options are non conventional source of energy.
Match the following with correct response.
Suffocation and headache can be caused by carbon monoxide, Green house effect is due to Carbon dioxide, Acid rains are due to sulphur dioxide and smog is as a result of Nitrogen dioxide.
How many number of neutrons are released in a fission of U – 235?
A uranium-235 atom absorbs a neutron and fissions into two new atoms (fission fragments), releasing three new neutrons and some binding energy.
Match the following with the correct response.
(1) The group of solar cells joined together in definite pattern is solar panel---Solar panels are those devices which are used to absorb the sun's rays and convert them into electricity or heat. Description: A solar panel is actually a collection of solar (or photovoltaic) cells, which can be used to generate electricity through photovoltaic effect
(2) The device used for obtaining energy for flowing water is water wheel----A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill
(3) A barrier constructed on the river to store the flowing water is dam---A dam is usually constructed across a river to create a reservoir in the valley behind by storing the water that flows into it naturally. ... Small rivers and streams are usually diverted through a tunnel, or a channel that is constructed around the side of the dam
(4) A domestic fuel which contains butane is LPG---Liquefied petroleum gas or liquid petroleum gas (LPG or LP gas), also referred to as simply propane or butane, are flammable mixtures of hydrocarbon gases
A solar water heater cannot be used on?
Solar heater works with the help of sunlight but on a Cloudy day there is no sunlight on earth as result of which solar heater will not work .
Name the disease which is likely to be caused due to ozone layer depletion
Ozone layer is important because it prevents too many harmful ultra violet rays from reaching earth. Ultra violet rays have the capability to destroy plants and animals and can cause skin cancer, cataracts to human beings. Existence of life on earth is possible only because of the presence of ozone layer around the earth
Water harvesting is an age-old concept in India. Various methods are used in different regions of India. Khadins water harvesting method is used in
A khadin, also called a dhora, is an ingenious construction designed to harvest surface runoff water for agriculture. Its main feature is a very long (100-300 m) earthen embankment built across the lower hill slopes lying below gravelly uplands. Sluices and spillways allow excess water to drain off. The khadin system is based on the principle of harvesting rainwater on farmland and subsequent use of this water-saturated land for crop production.
First designed by the Paliwal Brahmins of Jaisalmer, western Rajasthan in the 15th century, this system has great similarity with the irrigation methods of the people of Ur (present Iraq) around 4500 BC and later of the Nabateans in the Middle East. A similar system is also reported to have been practised 4,000 years ago in the Negev desert, and in southwestern Colorado 500 years ago.
Name the process that is a direct out come of excessive burning of fossil fuels
The burning of fossils fuels produces lots of CO2 that is one of the major green house gas. This has resulted in the increase in temperature on the earth called Global warming.
What happens when Hydrogen combines with oxygen in the presence of an electric current?
Hydrogen molecules violently react with oxygen when the existing molecular bonds break and new bonds are formed between oxygen and hydrogen atoms. As the products of the reaction are at a lower energy level than the reactants, the result is an explosive release of energy and the production of water
Match the following with the correct response.
oxidation is loss of electron and reduction is gain of electrons
Reducing agent is itself oxidized and oxidizing agent is itself reduced so reducing agent electron losing species and oxidizing one is electron gaining species
Mg ribbon burns with a dazzling flame in air (oxygen) and changes into a white substance, Magnesium oxide. Magnesium is
Mg gets oxidised by reacting with O2 to form MgO
A reaction which is opposite of combination reaction
(i) NH4Cl + Heat → NH3 + HCl
(ii) 2H2O + Electricity → 2H2 + O2
(iii) Fe + H2SO4 → FeSO4 + H2
Opposite to combination reaction means then the reaction should be decomposition reaction
Decomposition reaction: A reaction in which a single large compound splits into small compounds
Here decomposition reaction is taking place in i and ii options
Electric bulb filament is made of
Incandescent light bulbs consist of an air-tight glass enclosure (the envelope, or bulb) with a filament of tungsten wire inside the bulb, through which an electric current is passed.
Pyrolusite is an ore of:
Pyrolusite is a mineral consisting essentially of manganese dioxide (MnO2). It is an important ore of manganese. It is a black, amorphous mineral, often with a granular, fibrous or columnar structure.
Which of the following metals are obtained by electrolysis of their chlorides in molten state?
Highly reactive metals like Potassium, Sodium (Na), Calcium (Ca), Aluminium and Magnesium are obtained by electrolysis of their chlorides in molten state. They cannot be extracted by reducing their oxides with carbon. Iron (Fe) can be obtained from its oxide ore by reduction with coke or aluminium powder. Copper (Cu) can be obtained by heating its sulphide ore in air.
The following metals exist in their native state:
Platinum (Pt), Gold (Au) and Silver (Ag) occur in their free or native state.
The family of elements having seven electrons in the outermost shell is ______.
The halogens are located on the left of the noble gases on the periodic table. These five toxic, non-metallic elements make up Group 17 of the periodic table and consist of: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Although astatine is radioactive and only has short-lived isotopes, it behaves similar to iodine and is often included in the halogen group. Because the halogen elements have seven valence electrons, they only require one additional electron to form a full octet. This characteristic makes them more reactive than other non-metal groups.
Brass gets discoloured in air because of the presence of which of the following gases in air?
Brass gets discolored in air because of the presence of Hydrogen sulphide
It is because the presence of mixture of hydrogen and sulphide and brass is a type of thing which has a color very light and mixture is non temperature (hot and cold type of temperature) so it gets discolored.
The second ionization energy is greater than the first because
When one electron has been removed from the neutral gaseous atom, the positively charged ion formed has one electron less than the number of protons in the nucleus. As a result, the electrostatic attraction between the nucleus and the remaining valence electrons increases. Therefore, the second ionization enthalpy is greater than the first one.
P, Q, R are elements of Dobereiner’s triads. If the atomic mass of P is 7 and that of Q is 23, What will be the atomic mass of R?
According to Dobereiner's law of triads, when elements are arranged in the order of increasing atomic masses, groups of three elements having similar chemical properties are obtained. The atomic mass of the middle element of the triad is equal to the arithmetic mean of the atomic masses of the other two elements.
The basic nature of sodium hydroxide (NaOH) is due to the presence of ____________ in solution.
Any compound behaves as a base when it dissociates hydroxide ions (OH-) in its solution.
Ayush and Ishoo were given one test tube each. One of the test tube contained water and the other contained a solution of sodium hydroxide. They were asked to identify the test tube containing NaOH solution. Which one of the following can be used for correctly identifying the required test tube?
A base (NaOH) turns red litmus blue but a neutral compund (water) does not show any colour change.
You are provided with a sample and a strip of red litmus paper. How would you confirm the nature of the sample?
As here only red litmus is given therefore it could not indicate the acidic solution
therefore it is first dipped in Dil solution of NaOH so that it may turn blue and after that we pour drops of soln if the soln is acidic it would turn blue litmus to red and if it is basic it could remain in same colour and if it is neutral it colour changes to slightly yellowish
When HCl reacts with granulated zinc
Acids (HCl) reat with metals (Zn) to form salt and release hydrogen gas. The hydrogen gas evolved appears as bubbles.
The chemical compound present in a fruit is:
The esters are found naturally in fruits like apples, pears, bananas, pineapples, and strawberries. Fruits exhibit their aroma due to the presence of esters. Hence, it is said that esters have a fruity smell. Esters are also present in vegetables. CH3COOC2H5 is an ester.
When acetic acid reacts with ethyl alcohol, we add conc. H2SO4. It acts as _____________ and the process is called _____________.
The reaction in which a carboxylic acid combines with an alcohol to form an ester is called esterification. When acetic acid reacts with ethyl alcohol, an ester is formed along with water. Esterification is a reversible reaction. Concentrated sulphuric acid acts as a dehydrating agent and absorbs water from the product mixture so that the reaction proceeds in the forward direction. CH3COOH + C2H5OH --> CH3COOC2H5 + H2O
In an ecosystem, the 10% of energy available for transfer from one trophic level to the next trophic level is in the form of:
The autotrophs capture the energy present in sunlight and convert it into chemical energy. Therefore, the energy available for transfer from one trophic level to the next trophic level in an ecosystem is in the form of chemical energy. When one form of energy is changed to another, some energy is lost.
The driving force of an ecosystem is:
The driving force of an ecosystem is solar energy. A food chain in an ecosystem always starts with photosynthesis. The autotrophs or the producers are at the first trophic level. They fix up the solar energy and make it available for heterotrophs or the consumers.
Human being belongs to the species of
The billions of human beings living today all belong to one species: Homo sapiens. As in all species, there is variation among individual human beings, from size and shape to skin tone and eye color. But we are much more alike than we are different.
Who was the first scientist to isolate DNA?
DNA isolation is a process of purification of DNA from sample using a combination of physical and chemical methods. The first isolation of DNA was done in 1869 by Friedrich Miescher.
Rhizome, tuber, corm and bulb are under ground _____________ that help in vegetative propagation
Underground stem are modified plant structures that derive from stem tissue but exist under the soil surface
Testes in mammals descend into scrotum because
Scrotum lies outside the abdominal cavity. So, the temperature in scrotum is 2-3 degree less than the body temperature. And this temperature is required for the testis to produce sperms. So, that is why the testis descends into the scrotum.
Sperms can only be produced when testis is descended in the scrotum.
If a round, green seeded pea plant (RRyy) is crossed with wrinkled, yellow seeded pea plant (rrYY) the seeds to be produced is F, generation will be-
Since roundness and yellow colour are shown by capital letters in the genotype so they are dominant traits. We know that only dominant traits are expressed in F1 generation.
Who gave Germplasm Theory?
August Weismann (1834-1914) was a neo-Darwinian biologist who proposed the germplasm theory in his book Das Keimplasma.
He said that variations are of two types. Some are congenital i.e., organisms are born with them. Others are acquired during the life time of a particular plant or animal. It was with this latter type of variations, the acquired characters, that Weismann was very much concerned. He gradually developed his Theory of Germplasm to explain that acquired characters could not be inherited.
Which organ enables the developing foetus to obtain nourishment from the mother’s blood
Placenta connects the fetus to the uterine wall to uptake nutrients.
Which of the following method of reproduction induces over-crowding in plants
It is a quick method of multiplication Since the rate of multiplication is high there is overcrowding.
A trait in an organism is influenced by
As during fertilisation, sperm only gives nucleus, but ova gives nucleus as well as cytoplasm. Therefore, the mitochondrial DNA and other cytoplasmic factors are inherited directly from mother. there are some traits which are exclusively linked with Y- chromosome and they are inherited by the male child directly from father.
Between which two groups of vertebrates does archaeopteryx serve as connecting Link?
Archaeopteryx was a organism which provides the link between birds (aves) and reptiles because they had a beak and also teeth and they have wings like birds but also they have a long tail.