Question

why is it that water must be poured onto quicklime but quicklime cannot be dropped into water?

Answer 1

Dear student

The reaction of quick lime and water can be done both ways. In both cases slaked lime is produced.
CaO + H₂O --> Ca(OH)₂

But precaution wise , it is better to pour water slowly into quicklime, rather than dropping quick lime into water , because in the second case, dropping of quick lime may produce splashes/spurts which may harm the person performing this reaction.

Regards