Elements of which group form anions most readily?

Which among the following is $\underline{\text{NOT}}$ a mineral of chlorine?

The element which liberates oxygen gas from water is

What are the products formed when chlorine is passed through an aqueous hypo solution?

The colour of the $X_2$ molecules of group $17$ elements changes gradually from yellow to violet down the group. This is due to
[$A$] the physical state of $X_2$ at room temperature changes from gas to solid down the group
[$B$] decrease in $HOMO-LUMO$ gap down the group
[$C$] decrease in $\pi^*-\sigma^*$ gap down the group
[$D$] decrease in ionization energy down the group

Chlorine acts as a bleaching agent only in the presence of