Science-2004

CBSE-science-2004-class-10(2)

SECTION A

Question 1

How is the rate of reaction influenced by
a) raising the temperature of reactants?
b) Adding to the reacting mixture a product of reaction without change in volume?

Question 2

How are the molecules of aldehydes and ketones structurally different?

Question 3

Name one non-metal and one metal which are in liquid state at room temperature.

Question 4

Name two other planets of the Solar System which are similar to the Earth in composition and structure.

Question 5

How is the strength of the magnetic field at a point near a wire related to the strength of the electric current flowing in the wire?

Question 6

How is chloride of lime chemically different from calcium chloride? Why does chloride of lime gradually lose its chlorine when kept exposed to air?

Question 7

What is formalin? How does it react with Tollen’s reagent? State any one of its uses. (Out of syllabus)

OR

Complete the following reaction equations:
(i) CH3CH2OH+Na –>
H
|
(ii) H—-C=O+HCN–>(Out of syllabus)

Question 8

.What is a galaxy? Name two common shapes of galaxies. Why is our

galaxy called Milky Way?(out of syllabus)

Question 9

State one point of difference between a natural satellite and an artificial satellite. Name the type of orbit suitable for a geostationary satellite.

Question 10

Give one example of a nuclear fusion reaction. Describe one method for making such reactions possible.

Question 11

11.State Arrhenius’ concept of acids and bases. Giving reason, select a strong acid and a weak base from amongst the following substances:

H2CO3,HNO3, NaOH and NH4OH

Question 12

How is it that we can use detergents for washing clothes even when the water is hard, but not soaps?

What change has been made in the composition of detergents to make them biodegradable?

Question 13

Give reasons for the following:
a) Siliconcounts among metalloids.
b) Carbon is not used for making aluminum from aluminum oxide.
c) For making hydrogen by reaction with hydrochloric acid, granulated zinc is preferred to a block of zinc.

Question 14

Write chemical equations for reactions taking place when:
a) Zinc carbonate is calcined.
b) Ammonia gas is passed over heated copper (II) oxide.(Out of syllabus)
c) SO2 gas and H2S gas are together bubbled through water.(Out of syllabus)

Question 15

What are electrolytes? Define Faraday’s constant for electrolytic reactions. Find chemical equivalents of Cu (II) (at. wt. 63.5 and Ag(I) (at. wt. 108).

Question 16

A 5 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 30 cm. Find the (i) position, (ii) nature and (iii) size of the image formed.

Question 17

a) What is meant by ‘critical angle’ for a ray of light going from one medium into another?

b) What is the consequence of making angle of incidence of light, at an interface, greater than the critical angle?

c) Why does a cut diamond shine more than a glass piece with diamond cut?

Question 18

Why is it that iron does not occur as a metal in the crust of the earth? What are the common compound forms in which iron occurs? Which of these is more often used for extracting iron? Why are carbon and limestone mixed with the iron ore before feeding it into the blast furnace? Write the chemical equations for the reduction step and the slag formation step.

(Out of syllabus)

OR

Define an alloy and an amalgam. State the main constituents of the following alloys. In what property is each of them different from its main constituent:
(I) Stainless steel (II) Bronze?

Question 19

With the help of a labeled ray diagram, show the formation of image of an object by a compound microscope.
A compound microscope has an objective of focal length 0.5 cm and an eye-piece of focal length 2.5 cm. If its tube length is 25 cm, calculate what will be the magnifying power of the microscope.

Question 20

On what principle does a solar water heater operate? Draw a labeled schematic diagram for a solar water heater.
The solar constant at a place is 1.4 kW/m2. How much solar energy will be received at this place per second over an area of 5m2.

OR

What is the main basic cause for winds to blow? Name a part of India where wind energy is commercially harnessed. Compare wind power and power of water flow in respect of generating mechanical and electrical energies. What is the hindrance in developing them?

SECTION B

Question 21

State one of the evolutionary forces leading to the origin of a new species according to the synthetic theory of evolution.

Question 22

Name the excretory units present in an earthworm.

Question 23

A farmer floods his field everyday thinking that watering in this manner will result in a better yield of his wheat crop. What will be the result of this action of the farmer?

Question 24

Describe how the sex of the offspring is determined in the zygote in human beings.

Question 25

State any two practices which can help in the protection of our environment.

Question 26

.Define ‘nerve impulse’. Which structure in a neuron helps to conduct a nerve impulse

a) towards the cell body?
b) Away from the cell body?

Question 27

List the sequence of events that occur during the formation of a blood clot after an injury.

Question 28

What is potable water? State any four of its necessary characteristics.

Question 29

What is the function of gizzard in a grasshopper? Draw a labeled diagram showing the digestive system of a grasshopper.

Question 30

With the help of a labeled diagram describe double fertilization in plants.

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