Question

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

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

Answer 1

The Correct Option is A

Calgon is a water treatment agent, commonly used to soften hard water by chelating metal ions. Let us analyze each statement to determine which one is not true about Calgon:

1. Statement: Calgon contains the $2^{\text{nd}}$ most abundant element by weight in the Earth's crust.
   Explanation: Calgon is primarily composed of sodium hexametaphosphate, which primarily contains phosphorus and sodium as major elements. The most abundant element in the Earth's crust is oxygen, followed by silicon. Neither phosphorus nor sodium is the second most abundant element, making this statement incorrect.
2. Statement: It is a polymeric compound and is water soluble.
   Explanation: Calgon is indeed a polymeric compound and is water soluble, allowing it to effectively bind to calcium and magnesium ions in water.
3. Statement: It is also known as Graham's salt.
   Explanation: Graham's salt is another name for sodium hexametaphosphate, commonly used in water treatment as Calgon.
4. Statement: It does not remove $Ca^{2+}$ ion by precipitation.
   Explanation: Calgon works by binding to calcium ions and preventing them from forming precipitates, thus softening the water.

Therefore, the statement which is $NOT$ true about Calgon is: Calgon contains the $2^{\text {nd }}$ most abundant element by weight in the Earth's crust. This statement incorrectly claims the presence of the second most abundant element in Calgon, which is not true.