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

To solve the question, we need to determine which statement about Calgon is \(NOT\) true based on its characteristics and composition.

Calgon, commonly used in water treatment, is primarily composed of sodium hexametaphosphate (\(\text{Na}_6\text{P}_6\text{O}_{18}\)). It's important to analyze each given statement:

1. Calgon contains the \(2^{\text{nd}}\) most abundant element by weight in the Earth's crust.
   • The second most abundant element in the Earth's crust is Silicon (Si), whereas Calgon primarily contains phosphorus, oxygen, and sodium.
   • This statement is incorrect as Silicon is not a component of Calgon.
2. It is a polymeric compound and is water soluble.
   • Calgon is indeed a polymeric compound and it easily dissolves in water, which aids in water treatment by preventing the formation of scale.
   • This statement is correct.
3. It is also known as Graham's salt.
   • The name "Graham's salt" often refers to sodium hexametaphosphate, another name for Calgon.
   • This statement is correct.
4. It does not remove \(Ca^{2+}\) ion by precipitation.
   • Calgon sequesters calcium ions, preventing them from precipitating as scale. It operates by complexing with calcium ions, rather than by precipitation.
   • This statement is correct.

By analyzing each statement, we can conclude that the statement "Calgon contains the \(2^{\text{nd}}\) most abundant element by weight in the Earth's crust" is \(NOT\) true.

Thus, the correct answer is the first option: "

Calgon contains the \(2^{\text{nd}}\) most abundant element by weight in the Earth's crust.".