Saturday, September 1, 2012

Assignment Chemistry + Physics IX Summative assessment-1

Assignment Chemistry + Physics IX Summative assessment-1
1. You are provided with a mixture of naphthalene and ammonium chloride by your teacher. Suggest an activity to separate them with well labeled diagram.
 2. You want to wear your favorite 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?
3. Comment on the following statements:
(a) Evaporation produces cooling.
(b) Rate of evaporation of an aqueous solution decreases with increase in humidity.
(c) Sponge though compressible is a solid.
4. (a) Conversion of solid to vapour is called sublimation. Name the term used to denote the conversion of vapour to solid.
(b) Conversion of solid state to liquid state is called fusion; what is meant by latent heat of fusion?
5. Alka was making tea in a kettle. Suddenly she felt intense heat from the puff of steam gushing out of the spout of the kettle. She wondered whether the temperature of the steam was higher than that of the water boiling in the kettle. Comment.
6. Classify the following into osmosis/diffusion
(a) Swelling up of a raisin on keeping in water.
(b) Spreading of virus on sneezing.
(c) Earthworm dying on coming in contact with common salt.
(d) Shrinking of grapes kept in thick sugar syrup.
(e) Preserving pickles in salt.
(f) Spreading of smell of cake being baked through out the house.
(g) Aquatic animals using oxygen dissolved in water during respiration.
7. Salt can be recovered from its solution by evaporation. Suggest some other technique for the same?
8. While diluting a solution of salt in water, a student by mistake added acetone (boiling point 56°C). What technique can be employed to get back the acetone? Justify your choice.
9. What would you observe when
(a) a saturated solution of potassium chloride prepared at 60°C is allowed to cool to room temperature.
(b) an aqueous sugar solution is heated to dryness.
(c) a mixture of iron filings and sulphur powder is heated strongly.
10. Classify the following as physical or chemical properties
(a) The composition of a sample of steel is: 98% iron, 1.5% carbon and 0.5% other elements.
(b) Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.
(c) Metallic sodium is soft enough to be cut with a knife.
(d) Most metal oxides form alkalis on interacting with water.
11. Name the process associated with the following
(a) Dry ice is kept at room temperature and at one atmospheric pressure.
(b) A drop of ink placed on the surface of water contained in a glass spreads throughout the water.
(c) A potassium permanganate crystal is in a beaker and water is poured into the beaker with stirring.
(d) A acetone bottle is left open and the bottle becomes empty.
(e) Milk is churned to separate cream from it.
(f) Settling of sand when a mixture of sand and water is left undisturbed for some time.
(g) Fine beam of light entering through a small hole in a dark room, illuminates the particles in its paths.
12. Give an example each for the mixture having the following characteristics. Suggest a suitable method to separate the components of these mixtures
(a) A volatile and a non-volatile component.
(b) Two volatile components with appreciable difference in boiling points.
(c) Two immiscible liquids.
(d) One of the components changes directly from solid to gaseous state.
(e) Two or more coloured constituents soluble in some solvent.
Assignment for class IX Subject (Physics)
1. A particle is moving in a circular path of radius r. The displacement after half a circle would be:
(a) Zero (b )π r (c) 2 r (d) 2π r
2. A body is thrown vertically upward with velocity u, the greatest height h to which it will rise is,
(a) u/g (b) u2/2g
3.A passenger in a moving train tosses a coin which falls behind him. It means that motion of the train is
(a) accelerated (b) uniform (c) retarded (d) along circular tracks
4.A motorcyclist drives from A to B with a uniform speed of 30 km h–1 and returns back with a speed of 20 km h–1. Find its average speed.
5.Obtain a relation for the distance travelled by an object moving with a uniform acceleration in the interval between 4th and 5th seconds.
6.What is momentum? Write its SI unit. Interpret force in terms of momentum. Represent the following graphically (a) momentum versus velocity when mass is fixed. (b) momentum versus mass when velocity is constant.
7.Two objects of masses m 1 and m 2 having the same size are dropped simultaneously from heights h 1 and h 2 respectively. Find out the ratio of time they would take in reaching the ground. Will this ratio remain the same if (i) one of the objects is hollow and the other one is solid and (ii) both of them are hollow, size remaining the same in each case. Give reason

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