Fill in the blanks:

(a) Atoms are …………… .

(b) An ion with positive charge is called …………… .

(c) An ion with negative charge is called …………… .

(d) 2H₂ means two …………… of hydrogen.

(e) …………… is a triatomic molecule.

(f) Metals have …………… valency.

(g) Chemical name of caustic soda is …………… .

The valency of iron in Fe₂O₃ is:

1. 1
2. 2
3. 3
4. 6

The sulphate radical is written as SO₄^2-. What is the formula of calcium sulphate?

1. Ca(SO₄)₂
2. Ca₂(SO₄)
3. Ca(SO₄)₃
4. CaSO₄

Which of the following exhibits variable valency?

1. Calcium
2. Copper
3. Carbon
4. Chlorine