Available Answers

1. 1.

   Select the correct answers - from the choices 'A', 'B' or 'C'.

   1. The most abundant element in the universe.
      1. Oxygen
      2. Hydrogen
      3. Nitrogen
   2. An atom of hydrogen has - 
      1. 2 protons & 1 electron
      2. 1 proton & 2 electrons
      3. 1 proton & 1 electron
   3. Organic compounds contain -
      1. C, H, O
      2. C, H, N
      3. C, N, O
   4. Potassium reacts with cold water to give -
      1. Metal oxide
      2. Metal hydroxide
      3. Metal nitride
   5. The metal which reacts with steam and the reaction is reversible.
      1. Iron
      2. Magnesium
      3. Lead
   6. The metal zinc reacts with concentrated alkali solution to give -
      1. NaZnO₂
      2. Na₂ZnO
      3. Na₂ZnO₂
   7. The metal which displaces hydrogen from dilute hydrochloric acid is -
      1. Copper
      2. Iron
      3. Silver
   8. The most active metal from - potassium, sodium & calcium
      1. Calcium
      2. Sodium
      3. Potassium
   9. A metal which does not displace hydrogen from water.
      1. Mercury
      2. Zinc
      3. Aluminium
2. 2.

   Give balanced equations for the following conversions.

   1. A neutral liquid to hydrogen - using a metal above sodium in the reactivity series.
   2. Steam to hydrogen - using iron.
   3. An alkali to hydrogen - using lead.
3. 3.

   The diagram below shows the preparation of hydrogen from acidified water

   

   State whether the statements given below pertaining to preparation of hydrogen - by electrolysis of acidified water are true or false. If false write the correct statement.

   1. Electric current is passed through distilled water, acidified with dil. sulphuric acid.
   2. Distilled water conducts - electricity due to the presence of free ions.
   3. The electrode at end 'A' - connected to the positive end of the battery is called the cathode.
   4. Current enters the electrolyte - through the 'anode' and leaves through the 'cathode'.
   5. Electrolysis is the decomposition of a chemical compound [electrolyte] in the fused [molten] state only - by the passage of an electric current.
   6. The equation for electrolysis of acidified water is 
4. 4.

   The diagram below represents - the preparation of hydrogen in the laboratory.

   

   Answer the following:

   1. State what is added through the thistle funnel at end 'B'.
   2. Name the substance added in the flask 'A'
   3. Complete the word & molecular equation for the laboratory preparation of hydrogen.
      
   4. Complete the statements given below pertaining to collection of hydrogen by selecting the correct word/s in each case.
      1. Hydrogen is collected by _________________ displacement of water. [upward/downward]
      2. It is collected by the above method since it is _____________ soluble in water. [very slightly/fairly/highly]
      3. Hydrogen is lighter than air even then it is not collected by downward displacement of air, because it forms a/an ______________ mixture with air. [volatile/explosive]
   5. Give reasons for the following:
      1. Granulated zinc is preferred as the reactant in the above laboratory preparation.
      2. Dilute nitric acid is not preferred as a reactant in the above laboratory preparation.
      3. The end of the thistle funnel should dip below the level of the dilute acid - in the flask 'A'.
5. 5.

   Complete the table given below pertaining to the production of hydrogen - by Bosch process.

   1. Production of - water gas.
      
      1. Give a balanced equation for the reaction.
      2. Is the reaction - exothermic or endothermic.
      3. Water gas is a mixture of _____________ & _____________ in the ratio ________________.
   2. Reduction of steam to hydrogen.
      
      1. Give a balanced equation for the reaction.
      2. Name the catalyst & promoter used.
      3. Give a reason why a promoter is added to the catalyst.
      4. Is the above reaction exothermic or endothermic.
   3. The hydrogen is separated from CO₂ & CO by -
      1. dissolving CO₂ in
         1. 'X' = ________________ [a neutral liquid]
         2. 'Y' = ________________ [an alkali]
      2. dissolving CO in -
         1. 'Z' = _____________________________
         2. 'Y' + CO₂ → Salt + H₂O
            Give a balanced equation 
6. 6.

   Complete the table - by selecting the correct word/s in each case.

   Property of hydrogen
   1. Colour	a) greenish     b) pale yellow     c) colourless
   2. Odour	a) pungent      b) odourless       c) choking
   3. Density	a) lighter         b) heavier           c) same as - air
   4. Solubility	a) highly          b) very slightly    c) insoluble - in water
   5. Combustibility	a) combustible    b) non-combustible   c) suppporter of combustion   d) non-supporter of combustion
   6. Litmus	a) acidic to       b) alkaline to      c) neutral - to litmus