question_answer

  (a) When a white powder was mixed with dilute acid, a colourless and odourless gas was produced which turned lime water milky. What is this white powder? (b) Which one of the following set ups is the most appropriate for the evolution of hydrogen gas and its identification?

Answer:

  (a) White powder may be carbonate or bicarbonate, which evolves CO2 on reacting with dilute acid. CO2 gas turnes lime water milky.                                                                                                                                                             (1) (b) Set up (II) is the most appropriate for the evolution of H2 gas and its identification It is because the gas evolved is tested properly such that delivery tube does not dip in the solution.        (1)