Question

Point the odd one out and give the reasons for your choice.

• A. $\mathrm{Ammonium}\mathrm{ion}$
• B. $\mathrm{Sulphate}\mathrm{ion}$
• C. $\mathrm{Chloride}\mathrm{ion}$
• D. $\mathrm{Nitrate}\mathrm{ion}$

Answer 1

The correct option is A

$\mathrm{Ammonium}\mathrm{ion}$

The explanation for the correct answer

Option A

Ions

• Atoms become charged by donating or gaining electrons, these are called ions.
• By donating electrons, the atom will form a positively charged species known as a cation.
• By gaining electrons, the atom will form negatively charged species known as anions.
• The $\mathrm{Ammonium}$ cation is a positively charged polyatomic ion with chemical formulae ${{\mathrm{NH}}_4}^{+}$
• They are formed by the protonation of $\mathrm{Ammonia}\left({\mathrm{NH}}_3\right)$.

The explanation for the incorrect answer

Option B

• $\mathrm{Sulphate}$ anion is a polyatomic ion with chemical formulae ${{\mathrm{SO}}_4}^{2-}$.
• It is a salt of $\mathrm{Sulfuric}\mathrm{acid}\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$.

Option C

• $\mathrm{Chloride}\mathrm{ion}$ is the ${\mathrm{Cl}}^{-}\mathrm{anion}$.
• It is formed when $\mathrm{Chlorine}\left(\mathrm{Cl}\right)$ accept an electron from any atom.

Option D

• $\mathrm{Nitrate}$anion is a polyatomic ion with chemical formulae ${{\mathrm{NO}}_3}^{-}$.
• Salts containing these salts are called $\mathrm{Nitrates}$.

Thus, option A i.e., $\mathrm{Ammonium}\mathrm{ion}$$\left({{\mathrm{NH}}_4}^{+}\right)$ is the correct option.