The least active halogen with hydrogen is

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

Write a note on metal halides. Explain the reactivity of halogens with metals. Write a short note on interhalogen compounds.

The products obtained when chlorine gas reacts with cold and dilute aqueous $NaOH$ are:

Which of the following reactions proves the chlorinating property of phosphorus pentachloride?

Which of the following statements is correct?