(a) Baking soda is sodium hydrogencarbonate.
On heating, it is converted into sodium carbonate which is bitter to taste
\(2NaHCO_3\overset{Heat}\rightarrow Na_2CO_3 + H_2O + CO_2\)
(b) Baking soda can be converted into baking powder by the addition of appropriate amount of tartaric acid to it.
(c) The role of tartaric acid is to neutralise sodium carbonate and cake will not taste bitter