A piece of paper is burnt in air, the gas produced is passed through distilled water, the pH of water will be

Explanation

When paper, which is composed of organic material, is burnt, carbon dioxide (CO2) is produced. When CO2 is passed through distilled water, it reacts to form carbonic acid (H2CO3), a weak acid. This reaction slightly lowers the pH of the water from 7 to around 6.8, making Option C the correct choice. Option A is incorrect because it assumes no change in pH, which does not account for the acidic nature of carbonic acid. Option B assumes a stronger acidity than what carbonic acid would produce, and Option D indicates a very strong acid, which is not the case here.