Question 07.
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 colour of this pH paper to greenish-blue ?

(a) Lemon juice
(b) Vinegar
(c) Common salt
(d) An antacid

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Solution

pH paper turns greenish blue (i.e pH = 8) when it comes in contact with weakly basic compound and antacids contain weak base usually ${Mg(OH)}_{2}$ . Hence, an antacid would change the colour of the pH paper to greenish-blue.

Other options (a) and (b) contain acids and option (c) is a neutral salt.

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Question 07. 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 colour of this pH paper to greenish-blue ? (a) Lemon juice (b) Vinegar (c) Common salt (d) An antacid

pH paper turns greenish blue (i.e pH = 8) when it comes in contact with weakly basic compound and antacids contain weak base usually Mg(OH)2. Hence, an antacid would change the colour of the pH paper to greenish-blue. Other options (a) and (b) contain acids and option (c) is a neutral salt.

Question 07.
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 colour of this pH paper to greenish-blue ?

(a) Lemon juice
(b) Vinegar
(c) Common salt
(d) An antacid