Q.1. Rate of diffusion is faster in gases. Why?
Ans. The molecules of gases have larger intermolecular space and higher kinetic energy (speed), so they diffuse fast.
Q.2. On converting 250C, 380C and 660C to Kelvin scale, the correct sequence of temperature will be:
(a) 398K, 311K and 339K
(b) 398K, 300K and 338K
(c) 273K, 278K and 543K
(d)398K, 310K and 338K
Which condition out of the following will increase the evaporation of water?
(a) Increase in temperature of water
(b) Decrease in temperature of water
(c) Less exposed surface area of water
(d) Adding common salt to water
Ans. (a) 298 K, 311 K and 339 K
On converting 25°C, 38°C and 66°C, to Kelvin scale, we get the following temperatures:
25°C + 273 = 298 K
38°C + 273 = 311 K
66°C + 273 = 339 K
(a) Increase in temperature of water
On increasing the temperature, kinetic energy of water molecules increases and more particles get enough kinetic energy to go into the vapour state. This increases the rate of evaporation. On the other hand, decrease in temperature of water, less exposed surface area of water and addition of common salt to water decreases the rate of evaporation.
Q.3. A decibel is a
(a) musical instrument
(b) musical note
(c) measure of sound level
(d) noise meter
Ans. (c) A decibel is a measure of sound level. In other words, loudness of sound is expressed in decibel unit.
Q.4. Question number 4 is based on the paragraph given below. Study this paragraph and answer the questions that follow.
The pressure exerted by air is called atmospheric pressure. The pressure is generally measured in atmospheres. The atmospheric pressure at sea level is 1 atmosphere and is taken as normal atmospheric pressure.
1 atm = 760 mm of Hg = 76 cm of mercury
At a depth of 33 ft below the sea level, an additional 1 atm pressure is exerted by water. Other units of pressure are torr and bar. S.I. unit of pressure is pascal (Pa) (1 atm = 1.01 x 105 Pa) Applying pressure and reducing temperature can liquefy gases.
Have you heard of solid carbon dioxide (CO2)? It is stored under high pressure. Solid CO2 gets, converted directly to gaseous state on decrease of pressure to 1 atmosphere without into liquid state. This is the reason that solid carbon dioxide is also known as dry ice.
Thus, we can say that pressure and temperature determine the state of a substance, whether it will be solid liquid or gas.
1. When we blow air into a balloon, it inflates because
(a) air particles diffuse in balloon
(b) air particles collide with walls of balloon and exert pressure on them
(c) rubber is elastic in nature
(d) the temperature of air in the balloon becomes high
2. At a depth of 100 ft below sea level what is the value of total pressure experienced by a diver?
(a) 1 atm
(b) 2 atm
(c) 3 atm
(d) 4 atm
3. A pressure of 1520 mm of mercury is equal to:
(a) 1.5 atm
(b) 2 atm
(c) 1 atm
(d) 2.5 atm
4. Which is the most favourable condition for liquefaction of ammonia?
(a) Low pressure and low temperature
(b) High pressure and high temperature
(c) Low pressure and high temperature
(d) high pressure and low temperature
Q.5. Which of the following are exotic breeds?
(i) Brawn (ii) Jersey (iii) Brown Swiss (iv) Jersey Swiss
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)
Which one of the following nutrients is not available in fertilisers?
Ans. (b) (ii) and (iii)
Exotic breeds are those breeds that are not native to that place. Brown Swiss and Jersey are the exotic breeds of cow.
Fertiliser is a chemical or natural substance which is added to soil or land to increase its fertility. Iron is not availabel in fertilisers. They are composed of nitrogen, phosphorus and potassium compounds.
Q.6. A saturated solution is one in which
(a) no more solute can be added.
(b) no more solvent can be added,.
(c) solution becomes clear on heating.
(d) none of the above.
Ans. (a) no more solute can be added.
Q.7. Law of gravitation gives the gravitational force between:
(a) the earth and a point mass only
(b) the earth and Sun only
(c) any two bodies having some mass
(d) two charged bodies only
Q.8. A boy is whirling a stone tied with a string in a horizontal circular path. If the string breaks, the stone
(a) Will continue to move in the circular path.
(b) Will move along a straight line towards the centre of the circular path.
(c) Will move along a straight line tangential to the circular path.
(d) Will move along a straight line perpendicular to the circular path away from the boy.
Ans. (c) will move along a straight line tangential to the circular path
In circular motion, the direction of velocity at any point is always along the tangent at that point. If the string breaks, then the centripetal force acting on the stone becomes zero and it will move along a straight line tangential to the circular path.
Q.9. When we breathe in air, nitrogen also goes inside along with the oxygen. What is the fate of this nitrogen?
(а) It moves along with oxygen into the cell.
(б) It comes out with CO2 during exhalation.
(c) It is absorbed only by the nasal cells.
(d) Nitrogen concentration is already more in the cells so it is not at all absorbed.
Ans. (b) Any nitrogen that goes inside along with the oxygen comes out w ith CO2 during exhalation.
Q.10. Which of the following would weigh the highest?
(a) 0.2 mole of sucrose (C12H22O11)
(b) 2 moles of CO2
(c) 2 moles of CaC03
(d) 10 moles of H2O
Q.11. When a drop of blue ink is put in water, the blue colour spreads and the whole solution becomes blue. Name the phenomenon due to which this happens.
State one difference between gas and vapour.
Gas: It is a stable state as compared to vapour. e.g. O2H2.
Vapour: It is an unstable state. On normal cooling, capour changes into liquid state.
Q.12. Plants with undifferenttiated body design are grouped together as -------.
Q.13. For question numbers 13 and 14, two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (i), (ii), (iii) and (iv) as given below.
(i) Both A and R are true and R is correct explanation of the assertion.
(ii) Both A and R are true but R is not the correct explanation of the assertion.
(iii) A is true but R is false.
(iv) A is false but R is true.
Assertion: The fossil fuels like coal and petroleum contain small amounts of nitrogen and sulphur. When these fuels are burnt, nitrogen and sulphur too bum and this produces different oxides of nitrogen and sulphur.
Reason: Not only is the inhalation of these gases dangerous, they also dissolve in rain and give rise to acid rain.
(i) A (ii) B (iii) C (iv) D
Q.14. Study the composition of the two nuclei of two atomic species L and M.
L = protons 20, neutrons 20
M = protons 18, neutrons 22
Give the relation between the two.
Ans. L = nucleons = 20 + 20 = 40
M = nucleons = 18 + 22 = 40
Both have same atomic mass but different atomic number.
Relation between L and M : Isobars.
Q.15. (a) Why does our palm feel cold when we put some acetone or petrol or perfume on it?
(b) Why are we able to sip hot tea or milk, faster from a saucer rattier than a cup?
Ans. (a) Acetone, petrol or perfume has very low boiling temperature. When we put some acetone or petrol or perfume on our palm, the particles of it gain energy from our palm and evaporate quickly which cause cooling.
(b) The rate of evaporation increases with an increase of surface area in the case of saucer as compared to the cup and thus, hot tea or milk in saucer cools faster than cup. So, we are able to sip hot tea or milk faster from a saucer rather than a cup.
Q.16. (i) Name the two elemental forms in which carbon occurs.
(ii) Name any two forms in which carbon is found in combined state with other elements in nature.
(iii) Briefly explain how it can be said that all life forms are based on carbon containing molecules.
Ans. (i) Diamond, graphite.
(ii) As CO2 in air, as carbonate and hydrogen carbonate salts in minerals.
(iii) All living forms contain carbon in some form. It is a primary component of proteins, lipids, nucleic acids and carbohydrates which are essential for survival of living forms. It is also required in some form for various life processes like respiration, food metabolism etc.
Q.17. What is sound?
Draw a diagram showing sound wave propagation in air as density or pressure variations. Name the points where pressure or density are maximum and minimum respectively during its propagation.
Also show the amplitude (A) and wavelength (λ) in the diagram.
(а) How does loudness of a sound depend on (i) amplitude of wave, and (ii) distance between source of sound and the listener.
(b) Draw a diagram depicting soft sound and a louder sound. What is the main difference between the two?
Ans. Sound is a form of energy associated with vibrating objects and it causes a sensation of hearing in human ears.
The diagram showing sound wave propagation in air as density (pressure) variation has been shown in figure. Points having maximum pressure/density are known as “compressions” but points having minimum pressure/density are known as ‘rarefactions’. In figure, points C1, C2, C3, ... represent compressions and the points R1, R2, R3, ... represent rarefactions.
Amplitude 'A’ of oscillation and wavelength ‘λ' have also been shown in the diagram.
(a) (i) Loudness of a sound increases on increasing the amplitude of sound wave.
(ii) Loudness of a sound decreases on increasing distance of a listener from the source of sound.
(b) The diagrams have been shown in the following figure.
Louder sound has a greater amplitude but soft sound has a smaller value of amplitude.
Q.18. Describe the role played by the Lysosomes. Why these are termed as suicidal bags ? How do they perform their function?
Differentiate between diffusion and osmosis. Write any two examples where a living organism uses osmosis to absorb water.
Ans. Role : Digestion of foreign materials, digestion of worn out organelles. Because these burst themselves and digest their own cell.
Lysosomes are filled with digestive enzymes. Capable of breaking down all organic material.
Spontaneous movement of a substance from a region of high concentration to a region where its concentration is low, called diffusion. Osmosis is the passage of water from a region of high water concentration through a semipermeable membrane to a region of low water concentration.
(a) Unicellular freshwater organisms tend to gain water through osmosis.
(b) Plant roots absorb water through osmosis.
Q.19. You are provided with mixture of camphor, common salt and soil. Using various techniques how will you separate the components of this mixture. Write the various steps involved.
Describe an activity with labelled diagram to obtain dye from blue ink. Name the component which gets evaporated.
Ans. (i) First, heat the mixture. As camphor is sublimable, it will vapourise and so it can be separated through sublimation.
(ii) To separate mixture of common salt and soil, we will dissolve them in water. As salt is soluble in water and soil is not soluble in water soil can be separated through filtration.
(iii) At the end, we get salt solution. Salt can be separated from water by evaporation.
Fill half a beaker with water. Put a watch-glass on the top of the beaker. Add a few drops of blue ink on the watch-glass(as shown in the figure). Now, heat the beaker till a solid mass is obtained.
You will observe that a solid residue of the dye is obtained in the watch-glass. Ink is a colloidal solution. It is a heterogeneous mixture of dye and water Heating leads to the evaporation of water. This leaves behind the dye in the watch-glass.
Q.20. Out of solids, liquids and gases, which one has
(a) maximum movement of particles,
(b) maximum interparticle attractions,
(c) minimum space between particles?
Show that the state of matter can be changed into another state by changing the temperature. How can you show the interconversion of the states of matter?
Ans. (a) gases (b) solids (c) solids.
Change of state of matter by changing temperature is represented as under:
Interconversion of three states of matter is represented as figure.
Q.21. (a) What is immunisation?
(b) Define immunity and vaccination.
(c) Define vaccine.
(d) What type of diseases can be prevented through vaccination?
Ans. (a) Immunisation is a process of inoculation (injecting) of substance (vaccine) into a healthy person in order to develop immunity against the disease.
(b) Immunity is the ability of a body to recognise, destroy and eliminate external disease causing agents. This immunisation is done by giving vaccine and thus, it is also known as vaccination.
(c) The vaccine is a solution containing the disease-causing organisms in a diluted or weakened form. It may have organisms in living or even dead form.This does not actually cause the disease but this would prevent any subsequent exposure to the infecting microbe from turning into actual disease.
(d) Protection against diseases, like smallpox, rabies, polio, diphtheria, chickenpox and hepatitis, is provided through vaccination. It has been possible to eradicate smallpox from all regions of the world through a massive vaccination programme.
Q.22. Study the given figure and answer the following questions:
(i) What is the potential energy of the object of mass (m) at point B and C when it is raised from point A to B and B to C.
(ii) Calculate the potential energy of the object when raised directly from point A to C.
(iii) Calculate whether the same amount of work is done against the gravity in each case. Write your inference.
Here, the work done is equal in each case.
Q.23. Draw the diagram of an animal cell and label the following:
(i) Factory of ribosomes.
(ii) Power house of cells.
(iii) Waste disposal system of the cell.
(iv) Director/brain/control centre of the cell.
Ans. (i) Endoplasmic Reticulum
Q.24. There are three solids made up of a luminium, steel and wood, of the same shape and same volume. Which of them would have highest inertia?
Two balls of the same size but of different materials, rubber and iron are kept on the smooth floor of a moving train. The brakes are applied suddenly to stop the train. Will the balls start rolling? If so, in which direction? Will they move with the same speed? Give reasons for your answer.
Ans. Inertia depends on the mass of the object. The density of steel is more than that of aluminium and wood, so for the same shape and volume of the three, the mass of steel will be greater than the solids made of aluminium and wood. Hence, steel has highest inertia.
When train slows down, balls remain in motion due to inertia of motion. Hence, both the balls will start rolling in the forward direction. Since mass of both the balls is different, so they will move with different speeds.
SECTION - C
Q.25. You are provided w ith a mixture o f naphthalene an d ammonium chloride by your teacher. Suggest an activity to separate them with well labelled diagram.
Define the following terms: (any two)
(i) Rigidity (ii) Compressibility and (iii) Density
Compare any two states of matter on the basis of above defined properties.
Ans. Naphthalene is insoluble in water but soluble in ether an organic solvent. It is volatile at room temperature. Ammonium chloride is soluble in water and volatile at higher temperature. It decomposes on heating to dryness.
(i) Rigidity: Property of matter to maintain shape.
(ii) Compressibility: Property of matter by virtue of which molecules of matter can be brought closer.
(iii) Density: Property of matter defined as mass per unit volume.
Q.26. (a) A person weighs 110.84 N on moon, whose acceleration due to gravity is 1/6 of that earth. If the value of 'g' on earth is 9.8 ms-2. Calculate.
(i) 'g' on moon.
(ii) Mass of person on moon
(iii) Weight of person on earth
(b) How does the value of g on the earth is related to the mass of the earth and its radius? Derive it.
Q.27. (i) Define Isotopes and Isobars with examples.
(ii) Give electronic configuration of any one pair of isotopes and isobars.
Ans. (i) Isotopes: Isotopes are defined as the atoms of the same element having the same atomic number but different mass numbers. For example, protiumand deuterium
Isobars: Atoms of different elements having same mass number but with different atomic numbers are called isobars. For example,
Q.28. Give short answers:
(i) What is the role of proteins and lipids in the plasma membrane?
(ii) Why plasma membrane is called as selectively permeable?
(iii) What is the role of cellulose in cell wall?
(iv) What is meant by plasmolysis?
(v) What is the advantage of flexibility of cell membrane?
(vi) Name the process which is useful for the movement of substances like CO2 and O2 across the cell membrane.
(a) What role vacuoles play in a typical plant cell?
(b) What will happen if Golgi Apparatus is removed from the cell?
(c) Why the inner membrane of mitochondria deeply folded?
Ans. (i) They provide flexibility to the plasma membrane,
(ii) Because it regulates the flow of selected materials in and out of the cell.
(iii) It provides structural strength to plants. It also helps in the absorption of water thus, preventing desiccation of cell.
(iv) When a living plant cell loses water through osmosis, there is shrinkage of the contents of the cell away from the cell wall. This phenomenon is known as plasmoly sis.
(v) It enables the cell to engulf in food and other material from its external environment. This process is known as endocytosis and is useful for amoeba to acquire food.
(a) (i) Vacuoles are the storage sacs for solid or liquid contents.
(ii) In plant cells, vacuoles are full of cell sap and provide turgidity and rigidity to the cell.
(iii) Many substances which are important in the life of the plant cell are stored in vacuoles. These include amino acids, sugars, various organic acids and some proteins.
(b) The following things may happen in the cell if there was no golgi apparatus:
(i) There will be effect on the packaging and dispatching of different types of proteins to various targets, inside and outside the cell.
(ii) The products of the cell cannot be stored and modified further.
(iii) The formation of complex sugars from simple sugars cannot take place.
(iv) The formation of lysosomes will be affected. This may cause accumulation of worn out and dead organelles within the cell which may lead to cell death.
(c) The deeply folded inner membrane of mitochondria creates a large surface area for ATP generating chemical reactions.
Q.29. Explain Rutherford's α-particles scattering experiment with diagram and observations.
Ans. Rutherford bombarded a stream of α-particles on a thin gold foil.
(i) Most of the α-particles passed through the foil without any deflection.
(ii) A few α-particles were deflected through small angles and few through larger angles.
(iii) The number of α-particles that bounced back was veiy small.
The important conclusions drawn from the experiment are:
(i) An atom consists of positively charged centre called nucleus.
(ii) The electrons revolve around the nudeus in well defined orbits.
(iii) The size of the nucleus is very small as compared to the size of the atom.
Q.30. What are Vertebrates? Give some properties of the groups. In how many groups are vertebrates divided?
Ans. Vertebrates are animals that have a true vertebral column and internal skeleton, allowing a completely different distribution of muscle attachment points to be used for movement.
(а) Animals are bilaterally symmetrical, triploblastic and coelomate.
(b) It is a subphylum of those chordates in which the notochord has been replaced by an endoskeleton of vertebral column and cranium while the dorsal nerve chord has been transformed into brain and spinal cord.
(c) Like other chordate vertebrates exhibits complex differentiation of body tissues and organs, posses paired gill pouches and post anal tail during any stage of its lifecycle.
(d) They have ventral heart.
(e) They possess paired gill pouches during any stage of life.
Vertebrates are divided into five classes:
(i) Pisces- Includes fresh water and marine fishes.
(ii) Amphibia- They live on both land and water.
(iii) Reptilia- Are creeping, burrowing, cold-blooded generally land animals.
(iv) Aves- Warm-blooded, usually aerial
(v) Mammals- Warm-blooded, give birth to young ones.