Question

An oxide of a metal is found to contain 47.06% oxygen and its formula is M203. The atomic weight is

(a) 9 (b) 12 (c) 27 (d) 51​

Answer 1

Answer:

100 g of metal oxide will contain 40 g oxygen and 60 g metal.

Number of moles of oxygen

16g/mol

40g

=2.5mol

The valency of metal is 2. The formula of metal oxide will be MO.

Hence, number of moles of metal = number of moles of oxygen =2.5mol

The atomic weight of the metal is-

2.5

60

=24g/mol.

So, the correct option is A

Answer 2

Answer:

27g

Explanation:

You want atomic mass of M , I guess.

Take 100.0 g of M2O3.

This will contain

oxygen = 47.03 g

M = 100.0–47.03 = 52.97 g

47.03 g O = 47.03 g / 16 g/mol = 2.9394 mol

Compound is M2O3

52.97 g M = 2/3 * 2.9394 mol

52.97 g M = 1.9596 mol M

1 mol M = 52.97 g/1.9596 mol

1 mol M = 27.03 g/mol

Atomic mass M = 27 g.