Time : 2½ Hours Max. Marks : 60

General Instructions :

1. The question paper comprises of two sections A and B. You are to attempt both the sections.

2. The candidates are advised to attempt all the questions of Section A separately and Section B separately.

3. All questions are compulsory.

4. There is no overall choice. However, internal choice has been provided in two questions of five marks

category in Section A and one question of 2 marks category and one question of 3 marks category in section B. You are to attempt only one option in such questions.

5. Marks allocated to each question are indicated against it.

6. Questions 1 to 4 in Section A and 17, 18 in Section B are very short answer questions. These are to be answered in one word or one sentence only .

7. Questions 5 to 8 in Section A and 19, 20 in Section B are short answer questions. These are to be answered in about 30 – 40 words each.

8. Questions 9 to 14 in Section A and 21 to 23 in Section B are also short answer questions. These are to be answered in about 40 – 50 words each.

9. Questions 15, 16 in Section A and 24 in Section B are long answer questions. These are to be answered in about 70 words each.

SECTION — A

1. Which effect of electric current is used in coating nickel on an iron screw ?

2. How did the people in ancient days mark time on a clear night ?

3. Three solutions A, B and C have pH 2, 4 and 6 respectively. Which of the three solutions has maximum acid strength ?

4. Why is a negative sign used in the rate expression for the rate of a chemical reaction ?

5. You are given two fuse wires A and B with current rating 2A and 5A respectively. Which of the two wires would you select for use with a 1000W, 220V room heater ? Justify your answer.

6. State the law which relates the speed of recession of a galaxy to its distance from the earth. Represent the relation given by the law graphically.

7. A yellowish-white powder which smells of chlorine readily loses chlorine on exposure to air. It is also used for bleaching cotton and for disinfecting water.

( i ) Identify the yellowish white powder compound.

( ii ) Write balanced chemical equation representing the reaction involved in its manufacture.

8. Beside Baking Soda, what other ingradient does backing powder contain ? What is the role of baking powder in making of bread and cakes.

9. What is a wind energy farm ? Why is it essential to locate wind energy farms at specific locations ? List two limitations in harnessing wind energy.

10. Describe with a neat diagram an activity to show that a straight conductor carrying direct current produces a magentic field around it. State the rule which determines the direction of the magnetic field thus produced.

11. A person is unable to see the objects beyond 2m clearly. Name the defect of vision he is suffering from. List two causes due of which this defect may arise. Draw ray diagrams to show :

( i ) This defect of vision.

( ii ) Correction of this defect using appropriate lens.

12. What happens when :

( i ) Calcium reacts with water

( ii ) Iron reacts with steam

( iii ) Magnesium reacts with hot water

( iv ) Sodium reacts with water.

13. Name the gas which is hydride of a non-metal, has a characteristic pungent smell and is used in the manufacture of fertilizers, nitric acid and polymer. Draw a flow diagram with conditions involved to represent the manufacture of this gas.

14. What is an alloy ? Write the constituents of Duralumin, and Bronze. Give one use of each of them specifying the property on which it is based.

15. State the law which governs the strength of the current passing through a metallic conductor when a potential difference is applied across its ends. Illustrate this law graphically.

Three resistors each of resistance 10 ohm are connected, in turn, to obtain

( i ) minimum resistance

( ii ) maximum resistance

Compute

( a ) the effective resistance in each case

( b ) the ratio of the minimum to the maximum resistance so obtained.

OR

State the law which governs the amount of heat produced in a metallic conductor when electric current is passed through it for a given time. Express this law mathematically.

Two resistors of resistance 2 ohm and 4 ohm are, in turn, connected

( i ) in series

( ii ) in parallel to a given battery for same time interval.

compute the ratio of the total quantity of heat produced in the combination in the two cases.

16. A yellow non-metal brittle in nature, can be mined and is soluble in carbon disulphide.

( i ) Identify this non-metal

( ii ) Name its two allotropes

( iii ) How many atoms are present in its catenated molecule ?

( iv ) Write chemical equations to represent the reaction of this element with —

( a ) Concentrated Sulphuric Acid

( b ) Concentrated Nitric Acid 5

OR

A metal does not corrode when left exposed to air. It also occurs in nature in its oxide form and is used in thermit reaction.

( i ) Identify the metal.

( ii ) Describe the method used to enrich chief ore of this metal.

( iii ) Give two balanced chemical reactions in which this metal acts as a reducing agent.

SECTION — B

17. How many pairs of hepatic caeca are present in a grasshopper ?

18. Choose the non-biodegradable pollutants out of : domestic waste, plastics, radioactive waste, paper.

19. List two causes of depletion of ozone layer. Mention any two harmful effects of depletion of this layer.

20. State two vital functions of human kidney.

OR

Name four blood groups in human beings. State the possibility of blood donation by each group.

21. In what three ways respiration in plants differs from respiration in animals ?

22. Explain the terms ( i ) reflex action, ( ii ) reflex arc. Give two suitable examples of reflex action.

23. How many ‘x’ chromosomes are present in the body cells of humans in a ( i ) male and ( ii ) female ?

Describe the role of sex chromosomes in deciding the sex of the child.

OR

Define the terms ( i ) heredity, ( ii ) variation. What is the science of heredity and variation called ? Mention the contribution of Mendel in explaining the pattern of inheritance.

24. Draw the diagram of reproductive system of human female. Label fallopian tube, uterus, cervix and vagina. What is ovulation and when does it take place during the menstrual cycle ? Where does fertilization take place ?

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