Assertion (A): NiS and CoS are not precipitated by H2S in dilute HCl, yet once precipitated in ammoniacal medium they do

Question

Assertion (A): NiS and CoS are not precipitated by H2S in dilute HCl, yet once precipitated in ammoniacal medium they do not redissolve in cold dilute HCl. Reason (R): On standing, freshly precipitated NiS and CoS change to a form with a much lower solubility product.

Accepted Answer

Both A and R are true and R is the correct explanation of A

Answer

Both A and R are true but R is not the correct explanation of A

Answer

A is true but R is false

Answer

A is false but R is true

Assertion (A): $NiS$ and $CoS$ are not precipitated by $H X_{2} S$ in dilute $HCl$ , yet once precipitated in ammoniacal medium they do not redissolve in cold dilute $HCl$ . Reason (R): On standing, freshly precipitated $NiS$ and $CoS$ change to a form with a much lower solubility product.

Answer: A

More questions on Group IV cations (Zn, Mn, Ni, Co)

Assertion (A): NiS and CoS are not precipitated by HX2​S in dilute HCl, yet once precipitated in ammoniacal medium they do not redissolve in cold dilute HCl. Reason (R): On standing, freshly precipitated NiS and CoS change to a form with a much lower solubility product.

Answer: A

More questions on Group IV cations (Zn, Mn, Ni, Co)

Assertion (A): $NiS$ and $CoS$ are not precipitated by $H X_{2} S$ in dilute $HCl$ , yet once precipitated in ammoniacal medium they do not redissolve in cold dilute $HCl$ . Reason (R): On standing, freshly precipitated $NiS$ and $CoS$ change to a form with a much lower solubility product.