The gas which turns limewater milky is

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Q: 22 (CDS-II/2012)
The gas which turns limewater milky is

question_subject: 

Science

question_exam: 

CDS-II

stats: 

0,56,31,56,12,17,2

keywords: 

{'limewater milky': [0, 0, 0, 2], 'carbon dioxide': [2, 0, 5, 6], 'nitrogen dioxide': [3, 0, 1, 8], 'gas': [9, 1, 9, 27], 'carbon monoxide': [3, 0, 1, 1], 'ammonia': [0, 1, 0, 2]}

The correct answer is option 1: carbon dioxide. When carbon dioxide gas is passed through limewater (a solution of calcium hydroxide), it reacts to form calcium carbonate, which is a white precipitate. This reaction is commonly used as a test for the presence of carbon dioxide gas.

Option 2: carbon monoxide is not the correct answer. Carbon monoxide does not react with limewater to produce a milky white precipitate.

Option 3: ammonia is not the correct answer. Ammonia gas does not react with limewater to produce a milky white precipitate.

Option 4: nitrogen dioxide is not the correct answer. Nitrogen dioxide gas does not react with limewater to produce a milky white precipitate.

Overall, the gas that turns limewater milky is carbon dioxide, as it undergoes a chemical reaction with the calcium hydroxide in the limewater to form a white precipitate of calcium carbonate.