(a) Concentrated sulphuric acid is called the king of chemicals as it is a very strong acid and is highly corrosive.
(b)The three chemical reactions that take place during the conversion of sulphur dioxide to sulphuric acid in the ‘Contact Process’ are given below.
Step I: Sulphur dioxide is mixed with air and passed over vanadium (V) oxide catalyst heated to 450C to form sulphur trioxide.
Step II: Sulphur trioxide is dissolved in concentrated sulphuric acid to form a thick fuming liquid called oleum.
Step III: Oleum is diluted with a calculated quantity of water to obtain sulphuric acid.
(c) If water is added to sulphuric acid, then a large amount of heat is evolved. This changes water to steam, which can splash the acid. Hence, it is dangerous.