Question

A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the color of this pH paper to greenish-blue?

• A. Lemon juice
• B. Vinegar
• C. Common salt
• D. An antacid

Answer 1

The correct option is D

An antacid

The correct option is (D):

Explanation for the correct answer:

An Antacid:

1. Antacid is basically a substance which is just used to relieve the indigestion, that is caused by the too much of $\mathrm{HCl}$ secretion in the stomach.
2. As the acidity in the stomach causes the sensation of heatburn, so the antacids are just taken to relieve the sensation.
3. They are actually taken orally just to suppress the effects of acidity. And they are alkaline in nature that will neutralize the gastric acids of the stomach.
4. Now, as the solution of soil and water is acidic in nature as shown by the pH paper giving the color yellow-orange.
5. So, the antacid which is basic in nature that is a baking soda or Sodium bicarbonate or the Sodium hydrogen carbonate will change the pH paper from yellow-orange to green while the others are just acidic in nature.

Explanation for the incorrect answers:

Option (A):

Lemon juice:

1. As the solution of soil and water is acidic in nature as shown by the pH paper giving the color yellow-orange.
2. And Lemon juice is a rich source of Vitamin C that is actually a citric acid.
3. So, it will not change the color from yellow-orange to green.
4. Hence, this is an incorrect option.

Option (B):

Vinegar:

1. As the solution of soil and water is acidic in nature as shown by the pH paper giving the color yellow-orange.
2. And vinegar is actually a mixture of the Acetic acid and Water and also a mild acid.
3. So, it will not change the color from yellow-orange to green.
4. Hence, this is an incorrect option.

Option (C):

Common salt:

1. As the solution of soil and water is acidic in nature as shown by the pH paper giving the color yellow-orange.
2. And this common salt is Sodium chloride which has Sodium and the Chloride ions.
3. So, it can not bring the color change in the pH paper as only the base can bring this change.
4. Hence, this is an incorrect option.

Therefore, the correct option is (D): An antacid.