9. (i) A reddish-brown gas is obtained when X, Y and Z are separately warmed with concentrated sulphuric acid and copper turnings added to the mixture. INFERENCE 1: The common anion is the ........ ion.   10. (ii) When X is heated, it melts and gives off only one gas which re-lights a glowing splint. INFERENCE 2: The cation in X is either ....... or ......   11. (iii) The action of heat on Y produces a reddish-brown gas and a yellow residue which fuses with the glass of the test-tube. INFERENCE 3: The metal ion present in Y is the ......... ion.   12. (vi) When Z is heated it leaves no residue. Warming Z with sodium hydroxide solution liberates a gas which turns moist red litmus paper blue. INFERENCE 4: Z contains the .......... cation.   13. (v) Write the equations for the following reactions: 1. X and concentrated sulphuric acid (below 200°C). (One equation only for either of the cations given in INFERENCE 2.) 2. Action of heat on Y.