(i) Name the scientist whoprepared the first compound of noble gases
(ii) Give chemical reactions of `HNO_(3)` with iodine
(iii) Why are halogens coloured ?

Name the halogens that can form true chemical bonds with noble gases?

When you mix solutions of lead (II) nitrate and potassium iodide. (i) What is the colour of the precipitate formed ? Name the compound involved. (ii) Write a balanced chemical equation for the reaction (iii) Is this a double displacement reaction ?

A student perfomed the experiment of heating ferrous sulphate crystals in a boiling tube. He smelt fumes of a pungent gas and saw colours of ferrous sulphate disappear. (i) Write the chemical formula of the pungent gas. (ii) Why does the colour of crystal disappear ? (iii) Identify the nature of this chemical reaction.

(A) complete the following chemical equations : (i) Cu+HNO_(3) (dilute) to (ii) XeF_(4)+O_(2)F_(2)to (B) Explain the following observations: (i) Phosphorus has greater tendency for catentation than nitrogen. (ii) Oxygen is a gas but sulphur a solid. (iii) The halogens are coloured. Why ?

(a) Complete the followingh chemical reaction equations : (i) Cu+HNO_(3 (dilute))to (ii) P_4+NaOH+H_2Oto (b) (i) why does R_3P=O exist but R_3N=O does not ? (R=alkyl group) (ii) why is dioxygen a gas but sulphur a solid ? (iii) why are halogens coloured ?