Available Answers

1. 1.

   Give a chemical test to distinguish between the following gases:

   1. Hydrogen and oxygen
   2. Carbon dioxide and sulphur dioxide
   3. Hydrogen chloride and hydrogen sulphide
   4. Chlorine and nitrogen dioxide
   5. Ammonia and hydrogen chloride
   6. Sulphur dioxide and chlorine.
2. 2.

   On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate - relate to the reactions given below.

   1. A white substance which leaves an amphoteric oxide as a residue [whose colour varies in the heated and in the cold state] and evolves a gas which turns lime water milky.
   2. An efflorescent substance which leaves a residue having the same colour as the substance and evolves a gas which changes the colour of cobalt chloride paper.
   3. A white solid which evolves two colourless gases which on cooling combine and condense on the cooler parts of the test tube.
   4. A coloured substance which decomposes violently leaving a coloured residue and evolving two neutral gases one of which is unreactive or inert in nature.
   5. A coloured substance which leaves a black residue and evolves two gases one of which is acidic and coloured and the other neutral and colourless.
   6. A coloured substance which leaves on strong heating a black residue and evolves two colourless gases one of which is acidic and the other neutral.
   7. A white crystalline solid which decrepitates on heating leaving a residue which fuses with the glass and evolves two gases one of which is coloured and acidic.
   8. An amorphous substance which turns from pale green to black on strong heating evolving a colourless, acidic gas as the only gaseous product.
3. 3.

   Give balanced equations for the following conversions affected by heat alone on the substances:

   1. Copper carbonate to copper oxide ;
   2. Hydrated copper sulphate to sulphur dioxide;
   3. Copper nitrate to nitrogen dioxide;
   4. Ammonium dichromate to nitrogen;
   5. Zinc carbonate to zinc oxide;
   6. Zinc nitrate to nitrogen dioxide
4. 4.

   Using dilute sulphuric acid how would you differentiate between :

   1. Copper and magnesium
   2. Sodium carbonate, sodium sulphide & sodium sulphite.  

   How would you identify the gaseous products evolved.

5. 5.

   Using a platinum wire, conc. hydrochloric acid and a bunsen burner how would you between the three salts i.e. sodium chloride, potassium chloride and calcium chloride. Explain in brief the method used for the same.

6. 6.

   Using given samples of temporary and permanent hard water, soft water, ordinary soap, detergent and washing soda how would you -

   1. distinguish between hard and soft water
   2. distinguish between temporary hard water and permanent hard water
   3. remove temporary hardness from water without using a chemical compound
   4. remove temporary hardness and permanent hardness from water using a chemical compound
   5. prove the advantage of detergent over soap.