(i) Name the raw materials used in the manufacture of sodium carbonate by Solvay process.

(ii) How is the sodium hydrogen carbonate formed during Solvay process separated from a mixture of \(NH_4Cl\) and \(NaHCO_3\)?

(iii) How is sodium carbonate obtained from sodium hydrogen carbonate?

(i) An aqueous solution has a pH value of 7.0.  Is this solution acidic, basic or neutral?

(ii) If H+ concentration of a solution is \(1\times 10^{-2}\ mol\ L^{-1},\) what is the pH value for it?

(iii) Which has a higher pH value, 1 M HCl or 1 M NaOH solution?

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.

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 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.

(a) Why is sulphuric acid called 'King of Chemicals'?

(b) Describe the three chemical reactions that take place during the conversion of sulphur dioxide to sulphuric acid in the 'Contact Process'.

(c) Why should water be never added drop wise to concentrated sulphuric acid?

(i) Define universal indicator. For what purpose it is used?
(ii) Two solutions A and B have pH values of 3.0 and 9.5 respectively. Which of these will turn litmus solution from blue to red and which will turn phenolphthalein from colourless to pink?
(iii) Water is a neutral substance. What colour will you get when you add a few drops of the universal indicator to a test tube containing distilled water?

Account for the following:
(i) State the relation between hydrogen ion concentration of an aqueous solution and its pH.
(ii) An aqueous solution has a pH value of 7.0. Is this solution acidic, basic or neutral?
(iii) Which has a higher pH value, 1MHCl or 1MNaOH solution?
(iv) Tooth enamel is one of the hardest substances in our body. How does it undergo damage due to eating chocolates and sweets? What should we do to prevent it?
(v)How do [H⁺] ions exist in water?