Question #966b5

1 Answer
May 15, 2017

See below.

Explanation:

Test for Cr^(3+) is treating it with NaOH. It gives a grey-green precipitate which is soluble in excess NaOH to give a dark green solution.

Or you can treat it with aqueous NH_3 where it forms a grey-green precipitate and insoluble in excess ammonia.

It dissolves in dilute HCl to form solutions containing Cr^(2+). So it would be 3.