SECTION - A
Q.1. With which name is the phenomenon of changing of a liquid into its vapours at temperature below its boiling point known ?
Q.2. Earthquake produces which kind of sound before the main shock wave begins,
(c) Audible sound
(d) None of these
Earthquakes produces low frequency infrasound before the main shock waves begin which possibly alert the animals and they get disturbed
Q.3. A gun fires a bullet of mass m with a muzzle speed v. The kinetic energy of bullet is
(a) E = mv2
(b) E = 2mv
Kinetic energy of bullet
Q.4. Question is based on the paragraph given below. Study this paragraph and answer the questions that follow.
The phenomenon of change of liquid into vapours at any temperature below its boiling point is called evaporation. The rate of evaporation increases with increase in surface area, temperature, speed of wind and decrease in humidity. Evaporation causes cooling due to decrease in average kinetic energy of the remaining liquid; after the surface molecules leave. Lower the boiling point of the liquid, higher is its rate of evaporation.
We know that particles of matter are always moving and are never at rest. At a given temperature in any gas, liquid or solid, there are particles with different amounts of kinetic energy. In the case of liquids, a small fraction of particles at the surface, having higher kinetic energy, is able to break away from the forces of attraction of other particles and gets converted into vapour.
1. Synthetic clothes are uncomfortable in summer because:
(a) they absorb kinetic energy from the air molecules
(b) they do not let the sweat evaporate
(c) they are highly porous
(d) they are very thick
2. Liquids like ether and acetone are kept in cool places because :
(a) ether and acetone have high boiling points
(b) the rate of evaporation increases with surface area
(c) ether and acetone are volatile liquids with low boiling points
(d) ether and acetone have lower density than water.
3. The water spilled on the floor evaporates faster than the water in a glass due to:
(a) increase in surface area
(b) increase in temperature
(c) increase in humidity
(d) decrease in kinetic energy
4. During the process of evaporation, the particles of a liquid change into vapour state only:
(a) from the entire liquid
(b) from the bottom of the liquid
(c) from the surface of liquid
(d) from both surface and bulk of the liquid
Q.5. In which of the following conditions, the distance between the molecules of hydrogen gas would increase?
(i) Increasing pressure on hydrogen contained in a closed container.
(ii) Some hydrogen gas leaking out of the container.
(iii) Increasing the volume of the container of hydrogen gas.
(iv) Adding more hydrogen gas to the container without increasing the volume of the container.
(a) (i) and (ii)
(b) (i) and (iv)
(d) (ii) and (iv)
Ans: (c) (ii) and (iii)
Some hydrogen gas leaking from the container leaves some vacant space inside the container. So, hydrogen gas molecules inside the container occupy all the space available and the distance between the molecules of hydrogen gas will be increased.
Similarly, on increasing the volume of the container of hydrogen gas, more space will be available inside the container and hydrogen gas molecules will occupy all the space available. As a result, the distance between the molecules will be increased. So, option (ii) and (iii) will increase the distance between the molecules of hydrogen gas.
On the other hand, on increasing pressure, hydrogen molecules will come closer and the distance between them will be decreased. Also, on adding more hydrogen gas molecules without increasing the volume of container will decrease the distance between molecules.
Q.6. Tincture of iodine is a solution of
(a) iodine in water
(b) iodine in alcohol
(c) iodine in distilled water
(d) iodine in ether
Ans. (b) iodine in alcohol
Q.7. A girl stands on a box having 60 cm length, 40 cm breadth and 20 cm width in three ways. In which of the follow in g cases, pressure exerted by the brick will be:
(a) maximum when length and breadth form the base
(b) maximum when breadth and width form the base
(c) maximum when width and length form the base
(d) the same in all the above three cases
Q.8. A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled toad. The work done against the gravitational force will be (g = 10 ms-2)
(a) 6 x 103J
(b) 6 J
(c) 0.6 J
We know that, work done = F.D cos θ
Force on school bag makes an angle of 90° with the road i.e., θ = 90°
So, W = F.d cos 90°
Since, cos 90° = 0°, so, W = 0.
Hence, work done against the gravitational force is zero.
Q.9. Which one of the following is a correct definition of osmosis ?
(a) Movement of solute molecules from lower concentration to higher concentration through a semipermeable membrane.
(b) Movement of water molecules from a region of high solute concentration to a region of low solute concentration through a semipermeable membrane.
(c) Movement of solvent molecule from higher solute concentration to lower solute concentration through a permeable membrane.
(d) Movement of solvent molecules from low solute concentration to a region of high solute concentration through a semipermeable membrane.
Ans. (d) Osmosis is the phenomenon in which water molecules move through a semipermeable membrane from region of low solute concentration to the region of high solute concentration.
Q.10. Which of the following in Fig. do not represent Bohr's model of an atom correctly?
Q.11. Name the atmospheric gas that leads to global warming.
Ans. Carbon dioxide.
Q.12. Public Health Programme of childhood immunisation prevent___________ diseases.
Q.13. Assertion: Infectious diseases can be prevented by public health hygiene measures that reduce exposure to infectious agents.
Reason: Infectious diseases can also be prevented by using immunisation.
(i) A (ii) B (iii) C (iv) D
Q.14. A substance has a finite volume but not a definite shape. Write the physical state of substance.
Name the phenomenon of changing of a liquid into vapour at a temperature even below its boiling point.
SECTION - B
Q.15. You want to wear your favourite shirt to a party, but the problem is that it is still wet after a wash. What steps would you take to dry it faster?
Ans. Conditions that can increase the rate of evaporation of water are:
(a) an increase of surface area by spreading the shirt.
(b) an increase in temperature by putting the shirt under the sun.
(c) increase the wind speed by spreading it under the fan.
Q.16. (i) What is the cause of sensation of sound due to rolling of thunder?
(ii) Give the audible range of human ear.
(iii) What are infrasonic and ultrasonic waves?
When vertically jerk is given to a string, transverse waves are formed. Give three features of these waves.
Ans. (i) Repeated reflection/Reverberation is the cause of sensation of sound due to rolling thunder.
(ii) The frequency of audible range is 20 Hz to 20 kHz.
(iii) Frequency less than 20 Hz is infrasonic while greater than 20 kHz is ultrasonic.
Three features of transverse waves are:
(i) The particles of the medium vibrates at right angles to the direction of propagation of wave.
(ii) Transverse waves travels in the form of crests and troughs.
(iii) They cannot travel through liquids and gases.
Q.17. (a) How does velocity of sound change in air with (i) change in temperature, and (ii) change in air pressure?
(b) An observer standing at a seacoast observes 60 waves reaching the coast per minute. If the wavelength of a wave is 10 m, find the velocity of the wave.
Ans. (a) (i) The velocity of sound in air increases when atmospheric temperature rises.
(ii) The velocity of sound in air does not change (or remains unchanged) when the air pressure is either increased or lowered.
(b) Here frequency of waves v = 60 waves per minute = 60/60 waves per second = 1 Hz, and wavelength λ = 10 m.
∴ Velocity of the wave v = vλ = 1 x 10 = 10 ms-1.
Q.18. List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor? Why or why not?
Fungi are heterotrophic eukaryotic organisms and have cell wall made of chitin. Name five cell organelles that are present in the fungal cell. Also state two-structural differences between plant cell and fungal cell. Which life form occurs due to association of cells of fungi and algae?
Ans. When there is a disease, either the functioning or the appearance of one or more systems of the body will change for the worse. These changes give rise to symptoms and signs of disease. Symptoms of disease indicate that a person is not well. These symptoms can be in the form of headache, cough, loose motions or wound with pus. These symptoms indicate that there may be a disease, but they do not indicate what the disease is. Therefore, even if you have any of these symptoms, it is advisable to go to the doctor because he can only diagnose about any signs of a disease on the basis of these symptoms. These signs will give a little more definite indication of the presence of a particular disease. But if there is only one symptom of headache, then there is no need of visiting a doctor because it could be due to Tiredness or Stress.
1. Five cell organelles that are present in a fungal cell are:
(i) Nucleus, (ii) Mitochondria, (iii) Ribosome, (iv) Endoplasmic reticulum, (v) Golgi bodies.
2. Two-structural differences between plant cell and fungal cell are:
(i) The cell wall of plant cell is made-up of cellulose while the cell wall of fungal cell is made - up of chitin.
(ii) Plant cells have chloroplasts, whereas fungal cells do not have chloroplasts.
3. Some fungal species live in permanent mutually dependent relationship with blue-green algae (or cyanobacteria). Such relationships are called symbiotic. These symbiotic life forms are called lichens.
Q.19. (a) (i) Name the scientist who discovered neutrons.
(ii) What is the charge and mass of a neutron?
(iii) Where is neutron located in an atom?
(b) Helium atom has an atomic mass 4 u and its atomic number is 2. How many neutrons does it have?
Ans. (a) (i) James Chadwick
(ii) Charge = Zero,
Mass of neutron is equal to proton = 1 unit.
(b) Number of neutrons = Mass number - Number of protons = 4 - 2 = 2
Q.20. Write chemical formulae of all the compounds that can be formed by the combination of following ions:
Molar mass of nitrogen is 14 u. What will be the mass of one atom of nitrogen in grams?
Ans. Compounds of Ca2+
Compounds of K+
Compounds of Fe3+
Molar mass of nitrogen is 14 u
6.022 x 1023 atoms of nitrogen weigh = 14 g
1 atom of nitrogen weigh =
Q.21. Raju of Class IX was suffering from chickenpox. His friends Priya and Shaurya wanted to visit him. Shaurya's parents did not allow him to go. Priya already had suffered from it few months before. Priya1s parents allowed her to visit him. What could be the reason behind their parents' decision? What is the basis of principle of immunisation?
Ans. As Priya had already suffered from chickenpox few months back, her body has become immune to chickenpox-causing microbe. So, if that microbe enters her body again, her body would fight that microbe. Hence, her parents allowed her to visit Raju.
On the other hand, as Shaurya has never suffered from chickenpox, his body is not immune to chickenpox. Hence, his parents refused him to visit Raju.
Basis of principle of immunisation: It involves stimulating the host to develop immunity against dgent that causes disease. This is done by introducing weak microbes of that disease. Once the body starts making antibodies it can fight against the disease and body becomes immune against the disease.
Q.22. A cyclist moving along a circular path: of radius 63 m completes three rounds in 3 minutes. Calculate:
(i) The total distance covered by him during this time.
(ii) Net displacement of the cyclist.
(iii) The speed of the cyclist.
Ans. (i) Total distance covered
s = 2πr x t
s = 2πr x 3
(ii) Displacement = zero
Q.23. State one important function of each of the following:
(a) Glandular epithelium
(b) Nervous tissue
(c) Cuboidal epithelium.
Ans. (a) Glandular epithelium - Sometimes epithelial tissue exhibits inward foldings to form a multi-cellular gland which produces secretions like tears, mucus, gastric juice, intestinal juice and so on. Such an epithelium is referred as glandular epithelium.
(b) Nervous tissue - It coordinates the functioning of different body parts. It not only picks up sensations of all types but also provides response to all types of stimuli by transmitting impulses.
(c) Cuboidal epithelium - An epithelium which is composed of compactly arranged cells and appears squarish in vertical section and occurs in uriniferous tubules, germinal layers of sex organs, thyroid vesicles, small salivary and pancreatic ducts. Cuboidal epithelium takes part in secretion, excretion and absorption.
Q.24. Akhtar, Kiran and Rahul were riding in a motorcar that was moving with a high velocity on an expressway when an insect hit the windshield and got stuck on the windscreen. Akhtar and Kiran started pondering over the situation. Kiran suggested that the insect suffered a greater change in momentum as compared to the change in momentum of the motorcar (because the change in the velocity of the insect was much more than that of the motorcar). Akhtar said that since the motorcar was moving with a larger velocity, it exerted a larger force on the insect And as a result the insect died. Rahul while putting an entirely new explanation said that both the motorcar and the insect experienced the same force and a change in their momentum. Comment on these suggestions.
Explain the following:
(i) Why is it dangerous to jump out of a moving vehicle? How can the danger be minimised?
(ii) Why does a boatman push the water backward with the oars while rowing a boat?
Ans. Kiran's suggestion is not correct because momentum is always conserved, i.e., change in momentum of insect must be equal to that of motorcar.
Akhtar's suggestion is not correct for the same reason as above.
Rahul's suggestion is correct, i.e., insect and motorcar experience same force and change in momentum. However, the insect dies, because it is unable to bear the large force and large change in momentum.
(i) If a person jumps out of a moving vehicle, the feet will suddenly come to rest, while the rest of the body is in motion and hence he will fall down and may get hurt. This danger can be minimised by running along with moving vehicle in the same direction in which the vehicle is moving for some time, while jumping out of it.
(ii) When the boatman pushes the water backward with the oar, while rowing the boat then in accordance with Newton's third law of motion the water reacts back and pushes the boat in forward direction.
SECTION - C
Q.25. Write your observations when the following processes take place:
(a) An aqueous solution of sugar is heated to dryness.
(b) A saturated solution of potassium chloride prepared at 6080C is allowed to cool at room temperature.
(c) A mixture of iron filin g s and sulphur pow der is heated strongly.
(d) A beam of light is passed through a colloidal solution.
(e) Dil - HCl is added to the mixture of iron and sulphur.
Sidak took 5 moles of carbon atoms in a container and Sehaj also took 5 moles of sodium atoms in another container of same weight,
(a) Whose container is heavier?
(b) Whose container has more num ber of atoms?
Ans. (a) Sugar remains as residue in the form of a solid mass.
(b) Potassium chloride crystallises out.
(c) A black coloured compound is formed.
(d) The path of the light becomes visible.
(e) A colourless gas is evolved.
(a) Mass of sodium atoms carried by Sehaj = (5 x 23) g = 115 g
While, mass of carbon atom carried by Sidak = (5 x 12) g = 60 g
Thus, Sehaj's container is heavy.
(b) Both the containers have same number of atoms as they have same number of moles of atoms.
Q.26. (a) Give two reasons to support the statement that CO2 is a compound and not a mixture.
(b) Classify the following as pure substance or a mixture. If mixture,, indicate whether homogeneous or heterogeneous.
(i) 24 carat gold
(i) Name the separation techniques which you will apply for the separation of the following mixtures:
(a) Small pieces of metal in the engine oil of a car.
(b) Fine mud particles suspended in water.
(c) Oil from water.
(d) Sodium chloride from its solution in water.
(e) Camphor from salt.
(f) Wheat grains from husk.
(ii) Classify the following as a chemical or physical change:
(a) Water boils to form steam.
(b) Burning of paper.
(c) An almirah gets rusted.
(d) Making a fruit salad with raw fruits.
Ans. (a) (i) As compounds contain two or more elements combined in a fixed proportion, carbon and oxygen are present in a fixed ratio of 3 : 8 by mass in carbon dioxide.
(ii) As compounds cannot be broken down into simpler substances by chemical or electrochemical methods, the constituents of carbon dioxide cannot be separated by simple physical methods.
(b) (i) 24 carat gold is a pure substance.
(ii) Air is a homogeneous mixture in which the constituents are uniformly distributed throughout without any dear boundary of separation.
(iii) Concrete is a heterogeneous mixture that does not have uniform constituents.
(i) (a) Filtration.
(b) Sedimentation and Decantation.
(c) Separating funnel.
(ii) (a) Water boils to form steam : Physical change.
(b) Burning of paper : Chemical change.
(c) Ar. almirah gets rusted: Chemical change.
(d) Making a fruit salad with raw fruits : Physical change.
Q.27. (a) The following data represents the distribution of electrons, protons and neutrons in atoms of four elements A, B, C, D.
Answer the following questions:
(i) Write the electronic distribution in atoms of elements A and D.
(ii) Element A is an inert gas why?
(iii) What is the valency of element C?
(b) The average atomic mass of a sample of element X is 16.2 u. What are the percentages of isotopes of 16X8 and 18X8 respectively?
Ans. (a) (i) Electronic distribution in
Element A = 2, 8
Element B = 2, 8, 3
(ii) Element A is an inert gas because it has 8 electrons in the outermost shell.
(iii) The element C has electronic configuration 2, 8, 2. Hence, valency of C is 2.
(b) Suppose the percentage of 16X8 in the mixture is A.
Then percentage of 18X8 = 100 - A
Thus, percentage of 16X8 = 90
Percentage of 18X8 = 10
Q.28. We know that many human activities lead to increasing levels of pollution of the air, water bodies and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution?
Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.
Ans. Yes, definitely if these activities are isolated to specific and limited areas, then the level of pollution of the air, water bodies and soil will decrease. For example:
(i) If all the sewage discharge, industrial waste is collected and treated properly before discharging into water bodies, then obviously aquatic life in these water bodies will be affected to a little extent.
(ii) If hot water from the industries (which is used for cooling machines and other devices) is collected at a common place and cooled and aerated properly before discharging into water bodies. Then this will not affect the breeding capacity of aquatic organisms.
(iii) If all the industries and commercial places of a city/town are located in a particular area which is far away from a residential area. Then all diseases resulting from air pollution could be minimised.
(iv) Above all, it we use only biodegradable substances, then they will get decomposed easily and there will be very little pollution of our precious natural resources.
|1. Living cells with thin cell walls.||1. Living cells with slightly thick cell walls .||1. Dead cells with thick cell walls.|
|2. Cells are uniformly thin and are loosely packed with large intercellular spaces.||2. Cells are elongated and irregularly thickened at the comers with very little intercellular spaces.||2. Cells are long and narrow as the walls are thickened due to lignin (a type of cementing material). These walls are so thick that there is no internal space inside the cell.|
Q.29. (a) Analyse the reason behind the following statements:
(i) Epidermis is thicker in desert plants though it is usually single layered.
(ii) Presence of waxy layer (secreted by epidermis) on the outer surface of plants.
Ans. (a) (i) In such habitat, protection against water loss is essential.
(ii) Protecting against water loss, mechanical injury.
(b) Cells are elongated, flattened, closely packed. No intercellular spaces and form a continuous layer.
Q.30. Describe the structure of mitochondria with special emphasis on its membrane coverings. How can we relate the structure of the membrane with the function?
Ans. Mitochondria are rod shaped or sausage shaped cell organelles which are known as powerhouse of the cell. They contain enzymes necessary for the oxidation of food during the process of respiration and for release of energy in the form of ATP (Adenosine triphosphate).
ATP is also known as the energy currency of the cell. This energy is used by cell to perform various functions such as a mechanical work and biosynthesis of new chemical compounds.
Mitochondria is bounded by double membranes. The outer membrane is porous and the inner membrane is deeply folded. These folds are known as cristae and they provide a large surface area for ATP - generating chemical reactions. Mitochondria have their own DNA, ribosomes and enzymes to manufacture their own proteins. So they are also known as semiautonomous bodies.