Question

A compound contains $3.2\%$ of oxygen. The minimum molecular weight of the compound can be:

• A. 25
• B. 440
• C. 500
• D. 1000

Answer 1

Answer: (C)

500

Let the minimum molecular weight of the compound be $x$ g/mol.

It will contain at least 1 oxygen atom.
1 mole of compound contains $x$ g which corresponds to at least 1 oxygen atom or 16 g.

We know that for minimum molecular weight, there should be only 1 oxygen atom in the compound.

So, $x\times \frac{3.2}{100}=16⟹x=500g$.

Hence, the minimum molecular weight of the compound is 500 g.