Board Paper of Class 10 2013 Science - Solutions

Note:
1. Use the same answer-sheet for Section A and Section B.
2. Draw well-labelled diagrams wherever necessary.
3. All questions are compulsory.
4. Students should write the answers of questions in sequence.

Question 1

(A)

Fill in the blanks:

[2]

(1)

The chemical formula for rust is...............

(2)

The law used by Newlands to arrange elements is known as........... .

(B)

State whether the following statements are true or false:

[2]

(1)

The pH of rainwater is 7.

(2)

The SI unit of charge is volt.

(C)

Rewrite the following table so as to match the second and third columns with the first column:

Column I	Column II	Column III
1. Dispersion	Long-sightedness	Twinkling of stars
2. Refraction	Splitting of white light into component colours	Convex lens
3. Hypermetropia	Change in the direction of the ray of light due to change in medium	Spectrum of seven colours

[3]

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Question 2
Answer the following questions: [3 × 2 = 6]
(1) Distinguish between Conductors and Insulators.
(2) Why should the wires carrying electricity not be touched barefooted?
(3) Calculate the focal length of a corrective lens having power +2.5 D.
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Question 3
Answer the following questions (any four): [4 × 3 = 12]

(1) The atomic masses of three elements A, B and C having similar chemical properties are 7, 23 and 39, respectively.
(a) Calculate the average atomic mass of elements A and C.
(b) Compare the average atomic mass with atomic mass of B.
(c) What could the elements A, B and C be?

(2) When the substance ‘A’ is added to a solution of BaSO₄, a yellow precipitate is formed.
(a) What do you think substance A is likely to be?
(b) Name the precipitate.
(c) Which type of reaction is this?

(3) A person has sour taste in the mouth and a burning sensation of the stomach.
(a) What is he suffering from?
(b) Why does it happen?

(c) What substance is used as a remedy?

(4) Write any three properties of magnetic lines of force.

(5) Explain how the formation of a rainbow occurs. VIEW SOLUTION

Question 4

Answer the following (any one):			[5]
	(1)	What is myopia? Explain two possible reasons of myopia. How can it be corrected? Explain with a suitable diagram.
	(2)	Find the expression for resistors connected in series. Write any two characteristics of a series combination of resistors.

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Question 5

(A) Fill in the blanks:			[2]
	(1)	Dominant character masks the ............ character.
	(2)	........... artery takes the blood to the lungs for oxygenation.
(B) State whether the following statements are true or false:			[3]
	(1)	Roots of plants grow towards light.
	(2)	Hormones secreted by endocrine glands are directly released into the bloodstream.
	(3)	If the X chromosome is inherited from the mother and the Y chromosome from the father, then the offspring will be a male.
(C)	Write the structural formula of Methane.		[1]
(D)	Name the following: Metal which forms an amphoteric oxide.		[1]

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Question 6

Answer the following sub-questions:			[2 × 2= 4]
(1)	‘A’ is an element having four electrons in its outermost orbit. An allotrope ‘B’ of this element is used as a dry lubricant in machinery and in pencil leads. So
	(i)	Write the name of element ‘A’ and its allotropes.
	(ii)	State whether ‘B’ is a good conductor or non-conductor of electricity.
(2)	‘E’ is an element which reacts with oxygen to form an oxide E₂O. An aqueous solution of E₂O turns red litmus blue, so
	(1)	What is the nature of oxide E₂O?
	(2)	Write the name of element ‘E’.
(3)	Write two points of differences between arteries and veins.		1

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Question 7

*Answer the following questions (any four):*		[4 × 3 = 12]
(1)	Write any three differences between metals and non-metals with respect to their physical properties.
(2)	Define: (i) Saturated hydrocarbon (ii) Unsaturated hydrocarbon (iii) Catenation
(3)	Write the names and functions of three parts of the human nervous system in which it is divided.
(4)	What is meant by sexual reproduction? Name its two main processes.
(5)	Name any three parts of the female reproductive system in human beings. Write one function of each.

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Question 8

*Write the answer of`any one* question given below:**			[5]
	(1)	Write the names of different parts of the human digestive system and explain the functions of any three parts.
	(2)	Answer the following: (a) Draw a diagram of DNA showing genes. (b) What are the peculiarities of its structure?

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