Question

All metals are solid except

• A. Calcium $\left(\mathrm{Ca}\right)$
• B. Mercury $\left(\mathrm{Hg}\right)$
• C. Sodium $\left(\mathrm{Na}\right)$
• D. Potassium $\left(\mathrm{K}\right)$

Answer 1

The correct option is B

Mercury $\left(\mathrm{Hg}\right)$

On the basis of their properties, all the elements are classified into two main groups: metals and non-metals.

PROPERTIES OF METALS	PROPERTIES OF NON-METALS
1. Metals are malleable, i.e., they can be hammered into thin sheets and metals are ductile, i.e., they can be drawn into thin wires.	1. Non-metals are brittle (break easily). They are neither malleable nor ductile.
2. Metals are good conductors of heat and electricity.	2. Non-metals are bad conductors of heat and electricity. Exception- Graphite is a good conductor of electricity.
3. Metals are lustrous (shiny) and can be polished.	3. Non-metals are non-lustrous (dull) and cannot be polished. Exception- Iodine in a lustrous non-metal.
4. Metals are solids at room temperature. Exception- Mercury is a liquid metal.	4. Non-metals exist as solid, liquid and gas at room temperature.
5. Metals are generally hard. Exception- Sodium and potassium are very soft metals.	5. Non-metals are generally not hard. Exception- Diamond is a very hard non-metal.

The explanation for the correct option:

• Mercury $\left(\mathrm{Hg}\right)$ is the only metal that exists in a liquid state at room temperature.

The explanation for incorrect options:

• Calcium $\left(\mathrm{Ca}\right)$, Sodium $\left(\mathrm{Na}\right)$ and Potassium $\left(\mathrm{K}\right)$ are the solid metals. Therefore, (A), (C) and (D) are incorrect options.

Hence, the correct option is (B).