In the following schematic diagram for the preparation of hydrogen gas as shown in Figure, what would happen if following changes are made?

(a) In place of zinc granules, same amount of zinc dust is taken in the test tube.
(b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken.
(c) In place of zinc, copper turnings are taken.
(d) Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

For making cake, baking powder is taken.  If at home your mother uses baking soda instead of baking powder in cake,

(a) How will it affect the taste of the cake and why?

(b) How can baking soda be converted into baking powder?

(c) What is the role of tartaric acid added to baking soda?

A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back.  On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y; it gives a compound Z, used for disinfecting drinking water.  Identity X, Y, G and Z.

A dry pellet of a common base B, when kept in open absorbs moisture and turns sticky.  The compound is also a by-product of chlor-alkali process.  Identify B.  What type of reaction occurs when B is treated with an acidic oxide?  Write a balanced chemical equation for one such solution.

A sulphate salt of Group 2 element of the Periodic Table is a white, soft substance.  Which can be moulded into different shapes by making its dough.  When this compound is left in open for sometime, it becomes a solid mass and cannot be used for moulding purposes.  Identify the sulphate salt and why does it show such a behaviour?  Give the reaction involved.