Question

Why does hardness decrease with increasing molecular weight of the metals in the oxygen compounds?

Answer 1

Answer: Option (A)

Larger molecular weight means a smaller valence or charge on the metal, so making the bond between them weaker and the hardness lower

Explanation:

Hardness decrease with increasing molecular weight of the metals in the oxygen compounds, the reason for the decrease in hardness of the metals is due to chemical repulsion (inter molecular forces between atoms) which is greater when the metal and oxygen are close to each other making the compound hard.

If the repulsion is smaller, the compound has less hardness. So when the molecular weight is large, it has smaller valence or less charge on the metal which makes the bond weaker and less hard.