Atoms and Molecules Test

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Atoms and Molecules Test - 3

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Weekly Quiz Competition

Question 1
1 / -0

The mass percentage of hydrogen (H) in water is

A
11.11

B
1.11

C
88.88

D
8.88

Solution

Mass of hydrogen = 2 u

Mass of water = 2 + 16 = 18 u

Mass percentage of hydrogen in water = 2/18 x 100 = 100/9 = 11.11
Question 2
1 / -0

The ratio of H:O by mass in water is

A
1 : 8

B
8 : 1

C
2 : 1

D
1 : 2

Solution

2 molecules of hydrogen combine with 1 molecule of oxygen to form water.

Mass of H = 1 u

Mass of O = 16 u

Ration H:O = 2:16 = 1:8
Question 3
1 / -0

The indivisibility of atom was proposed by

A
de Broglie.

B
Bohr.

C
Rutherford.

D
Dalton.
Question 4
1 / -0

Copper reacts with oxygen to form two oxides, Cu2O and CuO. The ratio between the masses of copper which react with a fixed mass of oxygen is

A
63.5 : 16

B
63.5 : 8

C
2 : 1

D
1 :2

Solution

Mass of copper = 63.5

Ratio = Mass of Cu₂/Mass of Cu = 127/63.5 = 2/1 = 2:1
Question 5
1 / -0

The modern atomic symbols were proposed by

A
Bohr.

B
Dalton.

C
Berzelius.

D
none of these
Question 6
1 / -0

The mass of one Avogadro’s number of N atoms is equal to

A
14 amu

B
14 g

C
28 g

D
14 kg

Solution

one Avogadro’s number of N atoms = 14 g of N
Question 7
1 / -0

An atom is the

A
smallest particle of matter known

B
smallest particle of a gas

C
smallest indivisible particle of an element that can take part in a chemical change

D
radioactive emission.
Question 8
1 / -0

The mass of sulphur dioxide that will contain 6.023 x 1022 molecules is

A
0.64 g

B
32.0 g

C
6.4 g

D
64.0 g

Solution

No. of molecules in 64 g of SO₂ = 6.023 x 10²³

Mass of 6.023 x 10²² molecules of SO₂ = (6.023 x 10²²/6.023 x 10²³) x 64 g = 1/10 x 64 = 6.4 g
Question 9
1 / -0

The number of gram-molecules of O2 in 6.023 x 10²⁴ CO molecules is

A
1 gram-molecule.

B
0.5 gram-molecule.

C
5 gram-molecules.

D
10 gram-molecules.

Solution

1 mole of CO = 1 gram-atom of O or 6.023 x 10²³ molecules of CO = ½ gram molecule of O₂. Hence, 6.023 x 1024 molecules of CO = ½ x (6.023 x 10²⁴/6.023 x 10²³) = ½ x 10 = 5
Question 10
1 / -0

Which of the following is a binary compound?

A
H₂SO₄

B
CaCO₃

C
NaH

D
KNO₃

Solution

A binary compound contains two elements in it.

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Re-Attempt Weekly Quiz Competition

Atoms and Molecules Test - 3

Result

Atoms and Molecules Test - 3

Score

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SHARING IS CARING

Question 1

11.11

1.11

88.88

8.88

Solution

Question 2

1 : 8

8 : 1

2 : 1

1 : 2

Solution

Question 3

de Broglie.

Bohr.

Rutherford.

Dalton.

Question 4

63.5 : 16

63.5 : 8

2 : 1

1 :2

Solution

Question 5

Bohr.

Dalton.

Berzelius.

none of these

Question 6

14 amu

14 g

28 g

14 kg

Solution

Question 7

smallest particle of matter known

smallest particle of a gas

smallest indivisible particle of an element that can take part in a chemical change

radioactive emission.

Question 8

0.64 g

32.0 g

6.4 g

64.0 g

Solution

Question 9

1 gram-molecule.

0.5 gram-molecule.

5 gram-molecules.

10 gram-molecules.

Solution

Question 10

H2SO4

CaCO3

NaH

KNO3

Solution

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H₂SO₄

CaCO₃

KNO₃