X-2007

X-2007-science

SCIENCE AND TECHNOLOGY (Theory) 200

Time allowed: 2 hours 15 mins; Maximum Marks: 100

General Instructions:
1) The question paper comprises of two sections A and B. You are to attempt both sections.
2) You are advised to attempt all the questions of Section A and Section B separately.
3) All questions are compulsory.
4) There is no overall choice. However, internal choice has been provided in some questions. You are to attempt only one option in such questions.
5) Marks allocated to every question are indicated against it.
6) Questions number 1-4 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.
7) Questions number 5-8 in Section A and 19, 20 in Section B are short answer questions. These are to be answered in 30 – 40 words each.
8) Questions number 9-14 in Section A and 21 – 23 in Section B are also short answer questions.These are to be answered in 40 – 50 words each.
9) Questions number 15, 16 in Section A and 24 in Section B are long answer questions. These are to be answered in 70 words each.

SECTION A

Question 1

What is the role of a catalyst in a chemical reaction?

Question 2

Which class of compounds gives a positive Fehling’s test ?

Question 3

Approximately how many stars are there in the Milky Way ?

Question 4

What is meant by the statement, “Potential difference between points A and B in an electric field is 1 volt.”?

Question 5

State the ‘Law of Chemical Equilibrium’. Write an expression for the equilibrium constant (K) for the reaction, H2(g) + 3H2(g) —> 2NH3 + 92K

Question 6

Name the organic acid present in vinegar. Write a chemical equation which represents the commercial method for the preparation of this acid from ethanol.

Question 7

Distinguish between ‘artificial’ and ‘natural’ satellites. Why artificial satellites are called “eyes in the sky” ?

Question 8

An electric lamp is marked 100 W, 220 V. It is used for 5 hours daily. Calculate

(i) its resistance while glowing.

(ii) energy consumed in kWh per day.

Question 9

(a) Write the chemical name and formula of bleaching powder.
(b) Why does bleaching powder smell of chlorine when exposed to air?
(c) Write chemical equation to represent the action of dilute hydrochloric acid on bleaching powder.

Question 10

What is meant by ‘dehydrating agent’? Describe with a chemical equation, an activity to show that concentrated sulphuric acid is a strong dehydrating agent.

Question 11

Give reasons for the following :

(i) Oxidation of ethanol with CrO3 produces ethanal while ethanol when oxidised with alkaline KMnO4 produces ethanoic acid. (out of syllabus)

(ii) Propanone forms addition product with HCN.(out of syllabus)

(iii) Alcohol supplied for industrial purposes is mixed with copper sulphate.

Question 12

An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens.

Question 13

(a) State one limitation of solar energy available from solar cells.

(b) What is the minimum wind velocity required to obtain useful energy with a windmill?

(c) Define the term ‘nuclear fission’.

Question 14

(a) State Ohm’s Law.
(b) Draw a schematic diagram of the circuit for studying Ohm’s Law.

Question 15

(a) Name the chief ore of iron. Write its formula. (b)How is an iron ore concentrated? Describe it briefly. (out of syllabus)
(c)Draw a labeled diagram of the blast furnace used in the extraction of iron from its concentrated ore.

OR

(a) Draw a labeled diagram of ‘Frasch process’ used for extracting sulphur. (b) State the principle involved in the extraction of sulphur directly out of the ground.

Question 16

A 14-year old student is not able to see clearly the questions written on the blackboard placed at a distance of 5 m from him.
(a) Name the defect of vision he is suffering from.
(b) With the help of labeled ray diagrams show how this defect can be corrected.
(c) Name the type of lens used to correct this defect.

SECTION B

Question 17

Name the excretory unit of a kidney.

Question 18

What are phytohormones?

Question 19

Point out two differences between an artery and a vein.

OR

What is ‘osmoregulation ’? How does it take place in humans?

Question 20

Explain ‘reflex action’ with a suitable example.

Question 21

Explain double fertilization in plants.

Question 22

(a) What is a gene?
(b)Where are genes located?
(c) What is the nature of gene?

OR

Define ‘evolution’. Describe Darwin’s theory of evolution.

Question 23

What is ‘soil erosion’? Mention it’s any two effects. Suggest two ways by which soil erosion can be checked.

Question 24

(a) Draw a diagram of human ‘alimentary canal’.
(b) Label the following on the diagram drawn:
Oesophagus, Liver, Gall bladder, Duodenum
(c) What is the function of liver in the human body?

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