Atoms and Molecules Test

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Atoms and Molecules Test - 4

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Weekly Quiz Competition

Question 1
1 / -0

The percentage of water of crystallisation in CuSO₄.5H₂O is

A
36.07

B
72.14

C
9.02

D
56.15

Solution

Total mass of CuSO₄.5H₂O = (63.5 + 32 + 64) + (5×18) = 159.5 + 90 = 249.5

Percentage of water of crystallization = (90/249.5) x 100 = 36.07
Question 2
1 / -0

Which has the maximum number of atoms?

A
108 g of Ag

B
56 g of Fe

C
27 g of Al

D
24 g of 12C

Solution

To calculate no. of atoms, first calculate the mass of 1 atom. After that, divide the given mass by mass of 1 atom.

For example, Mass of 1 atom of O = 16 g

Therefore, No. of atoms in 32 g of O = 36/18 = 2
Question 3
1 / -0

8 g of O₂ has the same number of molecules as

A
22 g of CO₂

B
7 g of CO

C
14 g of CO

D
28 g of CO

Solution

Mass of O2 = 32g

No. of molecules in 8g of O2 = 32/8 = ¼

Mass of CO = 28g

No. of molecules in 7g of CO = 7/28 = 1/4
Question 4
1 / -0

A sample of pure water, irrespective of source, contains 88.89% oxygen and 11.11% hydrogen by mass. The data supports the

A
Law of conservation of mass

B
Law of constant composition

C
Law of multiple proportions

D
None of these
Question 5
1 / -0

10 g of CaCO₃ on heating gave 4.4 g of CO₂ and 5.6 g of CaO. The observation is in agreement with the

A
Law of constant composition

B
Law of conservation of mass

C
Law of definite proportion

D
Law of multiple proportion.
Question 6
1 / -0

The atomic mass of potassium is 39. The number of moles in 78 g of potassium is

A
78

B
39

C
2

D
1

Solution

Mass of 1 mole of potassium = 39 g

78 g of potassium = 78/39 = 2 mole
Question 7
1 / -0

The mass of sodium in 11.7 g of sodium chloride is

A
2.3 g

B
4.6 g

C
6.9 g

D
7.1 g

Solution

Mass of NaCl = 23 + 35.5 = 58.5 g = 1 mole of NaCl

11.7 g of NaCl = 11.7/58.5 = 0.2 mole

0.2 mole of Na = 0.2 x 23 = 4.6 g of Na
Question 8
1 / -0

The correct formula of aluminium sulphate is

A
Al₂SO₄

B
AlSO₄

C
Al₂(SO₄)₃

D
Al₃(SO₄)2

Solution

Valence of Al = 3+

Valence of SO₄ = 2-

Formula of aluminium sulphate = Al₂(SO₄)₃
Question 9
1 / -0

The formula unit mass of Na₂SO₄.10H₂O is

A
142 u

B
322 u

C
286 u

D
23 u

Solution

(46 + 32 + 64) + (10 x 18) = 142 + 180 = 322 u
Question 10
1 / -0

An element A is tetravalent and element B is divalent. The formula of the compound formed by these two elements is

A
AB₂

B
A₂B

C
A₂B₄

D
AB

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Re-Attempt Weekly Quiz Competition

Atoms and Molecules Test - 4

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Atoms and Molecules Test - 4

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Question 1

36.07

72.14

9.02

56.15

Solution

Question 2

108 g of Ag

56 g of Fe

27 g of Al

24 g of 12C

Solution

Question 3

22 g of CO2

7 g of CO

14 g of CO

28 g of CO

Solution

Question 4

Law of conservation of mass

Law of constant composition

Law of multiple proportions

None of these

Question 5

Law of constant composition

Law of conservation of mass

Law of definite proportion

Law of multiple proportion.

Question 6

78

39

2

1

Solution

Question 7

2.3 g

4.6 g

6.9 g

7.1 g

Solution

Question 8

Al2SO4

AlSO4

Al2(SO4)3

Al3(SO4)2

Solution

Question 9

142 u

322 u

286 u

23 u

Solution

Question 10

AB2

A2B

A2B4

AB

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22 g of CO₂

Al₂SO₄

AlSO₄

Al₂(SO₄)₃

Al₃(SO₄)2

AB₂

A₂B

A₂B₄