Match column I with column II and mark the correct option from the given codes. Column I Column II (a) 28 g of He (i) 58 . 5 u (b) 0 . 5 mole of O 2 (ii) 7 mol (c) Molecular mass of common salt (iii) 60 g (d) 1 . 5 mole of Ca (iv) 16 g

(a) - (ii), (b) - (iv), (c) - (i), (d) - (iii)

(a) - (iv), (b) - (ii), (c) - (iii), (d) - (i)

(a) - (ii), (b) - (i), (c) - (iii), (d) - (iv)

(a) - (ii), (b) - (iv), (c) - (iii), (d) - (i)

MEDIUM

9th Foundation

IMPORTANT

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$206 g$ of molten sodium bromide is decomposed electrolytically. The maximum mass of sodium obtained is [Atomic mass of $Na = 23 u, Br = 80 u$ ]

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Important Questions on Atoms and Molecules

MEDIUM

9th Foundation

IMPORTANT

NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 13

Four different experiments were conducted in the following ways :
I

3 g

of carbon was burnt in

8 g

of oxygen to give

11 g

{CO}_{2}

.
II

1.2 g

of carbon was burnt in air to give

4.2 g

{CO}_{2}

.
III

4.5 g

of carbon was burnt in enough air to give

11 g

{CO}_{2}

.
IV

4 g

of carbon was burnt in oxygen to form

30.3 g

{CO}_{2}

.
Law of constant proportions is illustrated in experiment(s)

HARD

9th Foundation

IMPORTANT

NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 14

Match column I with column II and mark the correct option from the given codes.

Column I		Column II
(a)	$28 g$ of $He$	(i)	$58.5 u$
(b)	$0.5$ mole of $O_{2}$	(ii)	$7 mol$
(c)	Molecular mass of common salt	(iii)	$60 g$
(d)	$1.5$ mole of $Ca$	(iv)	$16 g$

EASY

9th Foundation

IMPORTANT

NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 15

The atomic mass of oxygen is

16

and the molecular mass of ozone is

48

. What is the atomicity of ozone, if it is an allotrope of oxygen?

HARD

9th Foundation

IMPORTANT

NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 16

Two samples

X

and

Y

of a pure substance obtained by two different methods contain elements

P

and

Q

. Substance

X

has a mass of

2.25 g

and contains

0.90 g

Q

. Substance

Y

is made up of

60 % P

and

40 % Q

by weight. This is an illustration of

HARD

9th Foundation

IMPORTANT

NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 17

Which of the following represents the correct number of moles of each element in $40 g$ of ferric sulphate? [Atomic mass of $Fe = 56 u, S = 32 u, O = 16 u$ ]

	$Fe$	$S$	$O$
(A)	$2$	$3$	$12$
(B)	$1$	$1$	$4$
(C)	$0.2$	$0.3$	$1.2$
(D)	$0.1$	$0.1$	$0.4$

HARD

9th Foundation

IMPORTANT

NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 18

Which of the following molecules contains highest number of particles?

HARD

9th Foundation

IMPORTANT

NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 19

The graphical representation of number of molecules of different gases is given. Which gases are placed at correct position?

Question Image

HARD

9th Foundation

IMPORTANT

NSO Science Olympiad Workbook Grade 9>Chapter 3 - Atoms and Molecules>EXERCISES>Q 20

Sulphate of a divalent metal

M

exists in hydrated form. If

0.10

mol of metal sulphate combines with

9.0 g

of water to form the hydrated salt then, the formula of metal sulphate will be

206 g of molten sodium bromide is decomposed electrolytically. The maximum mass of sodium obtained is [Atomic mass of Na=23 u, Br=80 u]

Important Questions on Atoms and Molecules

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$206 g$ of molten sodium bromide is decomposed electrolytically. The maximum mass of sodium obtained is [Atomic mass of $Na = 23 u, Br = 80 u$ ]