Available Answers

1. 1.

   Select the correct gas from A to F which matches with the descriptions 1 to 5.

   A: CO₂       B: SO₂       C: NH₃          D: Water vapour        E: Cl₂          F: H₂S

   1. Turns moist blue litmus red and then bleaches it.
   2. Turns moist red litmus paper blue.
   3. Turns lime water milky and blue litmus paper slightly pink.
   4. Turns cobalt chloride paper from blue to pink.
   5. Turns lead acetate paper from white to Silvery black.
2. 2.

   Select the correct salt from list Il which on thermal decomposition exhibits the change in colour from list I - 1 to 5.

   List-I	List-II
   1. Light green to black	A: Copper carbonate
   2. White to yellow [heated state]	B: Hydrated Copper sulphate
   3. Blue to black	C: Copper nitrate
   4. Orange to green	D: Ammonium dichromate
   5. Blue to white	E: Zinc nitrate

3. 3.

   State which of the substances given below evolves oxygen gas on thermal decomposition.

   1. Zinc carbonate
   2. Washing soda
   3. Lead nitrate
   4. Ammonium dichromate
   5. Trilead tetroxide
   6. Zinc nitrate
   7. Mercury [Il] oxide
   8. Anhydrous copper sulphate
4. 4.

   Complete the table given below.

   1. Heat on copper nitrate	Colour of acidic gas evolved	____________________
   2. Heat on iodine crystals	Colour of vapours evolved	____________________
   3. Heat on ammonium dichromate	Name of neutral gas evolved	____________________
   4. Heat on copper carbonate	Test for gas evolved	____________________
   5. Heat on zinc nitrate	Colour of residue	____________________
   6. Addition of dil. H2SO4 to FeS	Odour of gas evolved	____________________
   7. Addition of dil. H2SO4 to KHCO3	Name of residue obtained	____________________
   8. Addition of dil. H2SO4 to zinc	Test for gas evolved	____________________
   9. Heat on sodium chloride	Colour imparted to flame during flame test	____________________
   10. Flame test for calcium chloride	Acid used for flame test	____________________

    

5. 5.

   Select the correct answer from the words in bracket.

   1. Hard and soft water can be distinguished using _______________ [dil. acid / ordinary soap / detergent]. 
   2. Household detergents contain mainly _______________ [carbonates/ phosphates] and pollute water bodies. 
   3. The type of water softened by addition of washing soda is _______________ [permanent/ temporary / both types].
   4. Unpolluted water has _______________ [high / low] amount of dissolved oxygen.
   5. The sample of hard water which lathers with soap after boiling & filtration contains _______________ [Calcium chloride / calcium bicarbonate].