Ammonia is made from its elements in the Haber process. Give the formula of ammonia. 

Ammonia is made from its elements in the Haber process. For the ammonium ion give formula.

(A) ${{\mathrm{NH}}_4}^{+}$                         (B) ${{\mathrm{NH}}_2}^{+}$                          (B) ${{\mathrm{NH}}_4}^{-}$

Enter your correct answer as A, B or C.

Give the formulae of the following ammonium salt: ammonium chloride.

$$\begin{gathered} \mathrm{A}:{\mathrm{NH}}_3\mathrm{Cl} \\ \mathrm{B}:{\mathrm{NH}}_4\mathrm{Cl} \\ \mathrm{C}:{\mathrm{NH}}_2{\mathrm{Cl}}_2 \end{gathered}$$

(Enter your correct answer as $\mathrm{A}, \mathrm{B} \mathrm{or} \mathrm{C}$)

Give the formulae of the following ammonium salt: ammonium nitrate.

$$\begin{gathered} \mathrm{A}:{\mathrm{NH}}_4{\mathrm{NO}}_2 \\ \mathrm{B}:{\mathrm{NH}}_3{\mathrm{NO}}_3 \\ \mathrm{C}:{\mathrm{NH}}_4{\mathrm{NO}}_3 \end{gathered}$$

(Enter your correct answer as $\mathrm{A}, \mathrm{B} \mathrm{or} \mathrm{C}$)

Give the formulae of the following ammonium salt: ammonium sulphate.

$\mathrm{A}: {\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4\mathrm{B}: {\left({\mathrm{NH}}_4\right)}_3{\mathrm{SO}}_4\mathrm{C}:\hspace{0.17em}\left({\mathrm{NH}}_4\right){\mathrm{SO}}_4$

(Enter your correct answer as $\mathrm{A}, \mathrm{B} \mathrm{or} \mathrm{C}$)

Phosphorus is the element below nitrogen in Group 15 of the periodic table. Its atomic number is $15$. 

Which molecule shows phosphorus in its lowest oxidation state?