Question

$\mathrm{Calgon}$ is used for water treatment. Which of the following statements is NOT true about $\mathrm{Calgon}$ ?

• A. $\mathrm{Calgon}$ contains the second most abundant element by weight in the earth's crust.
• B. It is also known as$\mathrm{Graham}’\mathrm{s}\mathrm{salt}$.
• C. It is a polymeric compound and is water-soluble.
• D. It does not remove ${\mathrm{Ca}}^{2+}$ion by precipitation.

Answer 1

The correct option is A

$\mathrm{Calgon}$ contains the second most abundant element by weight in the earth's crust.

The correct option is A.

Explanation for correct option:

(A) The chemical formula of Calgon is ${\mathrm{Na}}_6{\left({\mathrm{PO}}_3\right)}_6\mathrm{or}{\mathrm{Na}}_6{\mathrm{P}}_6{\mathrm{O}}_{18}$.

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, the second most abundant element in the earth’s crust is $\mathrm{Si}$ and it's not present in $\mathrm{Calogon}$.

Therefore, the statement that $\mathrm{Calgon}$ contains the second most abundant element by weight in the earth's crust is not true.

Explanation for incorrect options:

(B) ${\mathrm{Na}}_6{\left({\mathrm{PO}}_3\right)}_6\mathrm{or}{\mathrm{Na}}_6{\mathrm{P}}_6{\mathrm{O}}_{18}$ (Calgon) is also known as $\mathrm{Graham}\text{'}\mathrm{s}\mathrm{salt}(\mathrm{Sodium}\mathrm{hexa}\mathrm{meta}\mathrm{phosphate})$.

(C) It exists in polymeric form as $\mathrm{Na}{\left({\mathrm{PO}}_3\right)}_6$ and is water soluble.

(D) It removes ${\mathrm{Ca}}^{2+}$in soluble ion but not by precipitation.

Hence, Option A is correct.