One of the constituents of baking powder is sodium hydrogen carbonate, the other constituent is
(a) hydrochloric acid
(b) tartaric acid
(c) acetic acid
(d) sulphuric acid
Baking powder is a mixture of baking soda NaHCO3, (sodium hydrogen carbonate) and a mild edible acid such as tartaric acid. When baking powder mixes with water (for making cake or bread), sodium hydrogen carbonate reacts with tartaric acid to evolve carbon dioxide gas.
Hence, option (b) is the correct answer.