MCQ Online Test 2 of Chapter 3 Atoms and Molecules 2 Science| Class 9th Science

Questions :

1. The mass percentage of hydrogen (H) in water is
(a) 11.11
(b) 1.11
(c) 88.88
(d) 8.88

2. The ratio of H:O by mass in water is
(a) 1 : 8
(b) 8 : 1
(c) 2 : 1
(d) 1 : 2

3. The indivisibility of atom was proposed by
(a) de Broglie.
(b) Bohr.
(c) Rutherford.
(d) Dalton.

4. 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

5. The modern atomic symbols were proposed by
(a) Bohr.
(b) Dalton.
(c) Berzelius.
(d) none of these

6. 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

7. 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.

8. The mass of sulphur dioxide that will contain 6.023×10²² molecules is
(a) 0.64 g
(b) 32.0 g
(c) 6.4 g
(d) 64.0 g

9. 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.

10. Which of the following is a binary compound?
(a) H₂SO₄
(b) CaCO₃
(c) NaH
(d) KNO₃