In the following schematic diagram for the preparation of hydrogen gas as shown in the figure,what would happen if the following changes are made?
(i) In place of zinc granules, same amount of zinc dust is taken in the test tube.
(ii) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken.
(iii) In place of zinc, copper turnings are taken.
(iv) Sodium hydroxide is taken in place of dilute sulphuric acid and the test tube is heated.