Calgon is used for water treatment.
Question:

Calgon is used for water treatment. Which of the following statement is NOT true about Calgon?

1. Calgon contains the $2^{\text {nd }}$ most abundant element by weight in the Earth’s crust.

2. It is polymeric compound and is water soluble.

3. It is also known as Graham’s salt

4. It does not remove $\mathrm{Ca}^{2+}$ ion by precipitation.

Correct Option: 1

Solution:

$\rightarrow 2^{\text {nd }}$ most abundant element is “Si” and it is not present in calgon

$\mathrm{Na}_{6} \mathrm{P}_{6} \mathrm{O}_{18}=($ Graham’s salt $)$ (Sodium hexametaphosphate)

$\rightarrow$ It exist in polymeric form as $\left(\mathrm{NaPO}_{3}\right)_{6}$ and water soluble compound

$\rightarrow$ It removes $\mathrm{Ca}^{2+}$ in soluble ion but not by precipitation