Question

Which gas is used in preparation of soda water?
A. Carbon monoxide
B. Carbon
C. Sulphur
D. Chlorine
E. Carbon dioxide

Answer 1

Hint: Dissolved gas is an acidic gas, which adds a pleasantly acidic flavor and an interesting mouth-feel and effervescence. When this gas reacts with water it gives a mild or weak acid.
Complete step-by-step answer:

Carbon dioxide gas is used in the preparation of soda water. This process is known as carbonation and it is a process that causes the water to give effervescence. The reaction involved is given below:
\[C{{O}_{2}}+{{H}_{2}}O\to {{H}_{2}}C{{O}_{3}}\]
The amount of the carbon dioxide that can be dissolved in water is given by Henry's Law. As we know on increasing the temperature of solution the dissolved gas concentration decreases, to avoid this water is chilled, optimally to just above freezing, in order to permit the maximum amount of carbon dioxide to dissolve in it.
Hence, the correct answer is carbon dioxide \[\left( C{{O}_{2}} \right)\] which is option E.

Note: The dissolved gas stays in soda because water-soluble gases dissolve more easily in cold than in hot water. Compounds which are gaseous at room temperature can easily escape the liquid, given enough energy. Hence, the lower the temperature is the less energetic the molecules will be, and the longer they stay in solution. When beverages get warm, the gas molecules acquire more energy from their surroundings and leave quickly, and the soda gets flat faster.