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 also known as Graham’s salt.

3. It is polymeric compound and is water soluble.

4. It doesnot remove Cat ion by precipitation.

Correct Option: 1

Solution:

$\mathrm{Na}_{6}\left(\mathrm{PO}_{3}\right)_{6}$ or $\mathrm{Na}_{6} \mathrm{P}_{6} \mathrm{O}_{18}$

Order of abundance of element in earth crust is

$\mathrm{O}>\mathrm{Si}>\mathrm{Al}>\mathrm{Fe}>\mathrm{Ca}>\mathrm{Na}>\mathrm{Mg}>\mathrm{K}$

So second most abundant element in earth crust is Si not Ca.