Which of the following is a mixed salt?

Which of the following are the example of double salt?

(A) ${\mathrm{FeSO}}_4·{\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4·6{\mathrm{H}}_2\mathrm{O}$

(B) ${\mathrm{CuSO}}_4·4{\mathrm{NH}}_3·{\mathrm{H}}_2\mathrm{O}$

(C) ${\mathrm{K}}_2{\mathrm{SO}}_4·{\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3·24{\mathrm{H}}_2\mathrm{O}$

(D) $\mathrm{Fe}(\mathrm{CN}{)}_2·4\mathrm{KCN}$

Choose the correct answer.

State one relevant reason for the following:

• Hydrated copper sulphate crystals turn white on heating.

Answer the following:

Write the formula of a salt that contains water of crystsllisation.

State one relevant observation for the following reactions:

• Addition of excess ammonium hydroxide into copper sulphate solution.