Question

a student on adding achemical 'x' to rice extract observed that two solution turned blue black The chemical 'x'used could be

Answer 1

The solution could be iodine because iodine is a solution which on contact with starch gives blue black colour. And rice contains starch so the solution could be iodine.

Answer 2

It's iodine. Because rice contains starch and starch changes to blue black colour when iodine is added to it.