Question

Give the odd one out. Give reasons for your choice.

• A. $\mathrm{Helium}$
• B. $\mathrm{Neon}$
• C. $\mathrm{Argon}$
• D. $\mathrm{Magnesium}$

Answer 1

The correct option is D

$\mathrm{Magnesium}$

The explanation for the correct answer

Option D

• $\mathrm{Magnesium}$ is an element with symbol = $\mathrm{Mg}$.
• Atomic number of $\mathrm{Magnesium}$ = 12
• It belongs to group 2 and period 3.
• $\mathrm{Magnesium}$ is metal.

The explanation for the incorrect answer

Option A

• $\mathrm{Helium}$ is a chemical element with symbol = $\mathrm{He}$
• Atomic number = 2
• It belongs to group 18 and period 1.
• $\mathrm{Helium}$ is a noble gas.
• Noble gases are the gases that have completely filled the outermost shell. So they do not take part in a chemical reaction. They are stable in nature.

Option B

• $\mathrm{Neon}$ is a chemical element with symbol = $\mathrm{Ne}$
• Atomic number = 10
• It belongs to group 18 and period 2.
• $\mathrm{Neon}$ is a noble gas.
• They have completely filled the outermost shell. So they do not take part in a chemical reaction. They are stable in nature.

Option C

• $\mathrm{Argon}$ is a chemical element with symbol = $\mathrm{Ar}$
• Atomic number = 18
• It belongs to group 18 and period 2.
• $\mathrm{Argon}$ is a noble gas.
• They have completely filled the outermost shell. So they do not take part in a chemical reaction. They are stable in nature.

Thus, option D i.e., $\mathrm{Magnesium}$ is the correct option.