Question

which of the following metal on reaction with oxygen gives metal oxide containing 40% of oxygen by weight 1) Na 2) Mg 3) K 4) Ca

Answer 1

Explanation:

which of the following metal on reaction with oxygen gives metal oxide containing 40% of oxygen by weight

1) Na

2) Mg ✔

3) K

4) Ca

Explaination :-

Let's form the oxide of metal given in the question.

Oxides are :-

4Na + O2 → 2Na2O

2Mg + O2 → 2MgO

4K + O2 → 2K2O

2Ca + O2 → 2CaO

Now,

Let's calculate the molecular mass of all oxides formed.

Na2O = 23×2 + 16 = 46 + 16 = 62

MgO = 24 + 16 = 40

K2O = 39×2 + 16 = 78 + 16 = 94

CaO = 40 + 16 = 56

Now, Here we see that MgO contains 40 % oxygen by weight and it contains 60 % magnesium weight.

Calculation :-

→ 40 × 40/100

→ 40 × 2/5

→ 8 × 2

→ 16

And

→ 40 × 60/100

→ 40 × 3/5

→ 8 × 3

→ 24

From here, we see that MgO contains 60% magnesium and 40 % oxygen by its total weight.