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Hydrogen and Its Compounds

1. Incorrect statement among the following is
      1) H2 is used in the manufacture of Vanaspathi and bulk organic chemicals.
      2) H2 is used as a rocket fuel in space research.
      3) H2 is used in fuel cells.
      4) H2 can’t reduce Cu2O to Cu.
Ans: (4)
Explanation: Cu is present below H2 in reactivity series. Hence H2 can reduce Cu2O to Cu.

 

2. The law of constant composition does not hold good for the compound
      1) Sodium hydride             2) Calciumn oxide
      3) Zirconium Hydride        4) Carbondioxide
Ans: (3)
Explanation: Zr1H1.3 - 1.75 composition is neither 1 : 1 nor 1 : 2.

 

3. The bond angle and dipolemoment of water respectively are
     1) 109.5°, 1.84 D       2) 104.5°, 1.84 D      3) 104.5°, 1.48 D       4) 104.5°, 0 D
Ans: (2)
Explanation: Bond angle = 104.5°, V shape, μ = 1.84 D.

 

4. The correct order of dielectric constant values (at 298 K) of H2O2, H2O and D2O (in C2/N.m2)  is
       1) H2O2 > H2O > D2O        2) H2O > D2O > H2O2
       3) D2O > H2O > H2O2        4) H2O2 > D2O > H2O
Ans: (2)
Explanation: Dielectric constant of H2O = 78.39, D2O = 78.06, H2O2 = 70.7

 

5. The following reaction(s) can form gaseous product is/ are
       1) I2 + H2O2 + OH-        2) acidified KMnO4 + H2O2
       3) Both 1 and 2                 4) PbS + H2O2
Ans: (3)
Explanation: I2 + H2O2 + 2 OH-  2 I- + 2 H2O + O2
                      2 MnO-4 + 6 H+ + 5 H2O2  2 Mn+2 + 8 H2O + 5 O2
                    PbS + 4 H2O2  PbSO4 + 4 H2O

 

6. Zeolites are widely used 
     1) In cracking of Hydrocarbons                         2) In the conversion of alcohol into gasoline
     3) Ion exchanges in softening of hard water    4) All the above
Ans: (4)
Explanation: All are correct.

 

7. The correct order of abundance of (percentage of) water in human body, plants, estimated water supply from glaciers and rivers is
     1) Human body > Plants > Rivers > Glaciers
     2) Plants > Human body > Glaciers > Rivers
     3) Plants > Human body > Rivers > Glaciers
     4) Rivers > Plants > Human Body > Glaciers
Ans: (2)
Explanation: Plants = 95%, Human body = 65%, Glaciers = 2.04%, Rivers = 0.0001%.

 

8. Which of the following physical property for heavy water is lesser than that of water?
     1) Dielectric constant           2) Melting point
     3) Enthalpy of fusion           4) Enthalpy of vapourisation
Ans: (1)
Explanation: Dielectric constant of H2O = 78.39, D2O = 78.06.

 

9. Number of Oxygen atoms are present around each Oxygen atom in ice is
      1) 2      2) 3      3) countless      4) 4
Ans: (4)
Explanation: 4 Oxygen atoms around each Oxygen atom in tetrahedral manner.

 

10. The number of Hydrogen bonded water molecules in CuSO4. 5 H2O is
     1) 1      2) 2      3) 3      4) 4
Ans: (1)
Explanation: 4 H2O molecules are coordinated, outer 1 H2O molecule is hydrogen bonded [Cu(H2O)4]SO4 . H2O

 

11. Match the following.

The correct answer is          
           A     B     C    D              A      B     C      D     
      1) III    II    IV    V        2)  II   III     I     IV  
      3)  II     I    III   IV        4)   I    II     III   IV
Ans: (2)
Explanation: 2 is correct match.

 

12. The following oxyacid(s) involved in the preparation of H2O2 is/ are
       1) 50% H2SO4        2) H2S2O8       3) H2SO5        4) All the above
Ans: (4)
Explanation: 2 H2SO4  2 H+ + 2 HSO4- 
                      at anode: 2 HSO4-  H2S2O8 + 2 e-
                      H2S2O8 + H2O  H2SO4 + H2SO5
                      H2SO5 + H2O  H2SO4 + H2O2

 

13. Permanent hardness can be removed by
        1) Baking Soda         2) Washing Soda        3) Lime Water         4) Chile Salt Petre
Ans: (2)
Explanation: CaCl2 + Na2CO3  CaCO3 + H2O2
                             MgSO4 + Na2CO3  MgCO3 + Na2SO4

 

14. Insoluble Magnesium salt(s) formed after treating hard water with calculated amount of lime is/ are
        1) Mg(OH)2         2) CaCO3        3) both 1 & 2         4) MgCO3
Ans: (3)
Explanation: Mg(HCO2)2 + 2 Ca(OH)2  2 CaCO3
 + Mg(OH)2  + 2 H2O
                            Ksp of Mg(OH)2 = 18 × 10-11 - low
                            Ksp of MgCO3 = 3.5 × 10-8 - high
                            So, Mg(OH)2 is not formed.

 

15. Correct set(s) among the following is/ are
       a) CrCl3. 6 H2O – Coordinated water
       b) BaCl2. 2 H2O – Interstitial water
       c) CuSO4. 5 H2O – Hydrogen bonded water & coordinated water
       1) d, a, c, b          2) a, c            3) b, d           4) a, b, c only
Ans: (1)
Explanation: All are correct.

 

16. True peroxide among the following is
       1) SO2        2) NO2        3) MnO2        4) BaO2
Ans: (4)
Explanation: Ba+2 & O2-2 [Peroxide; Oxidation state of "O" = -1]

 

17. Molarity of 11.2 volume H2O2 solution is
       1) 1.0        2) 0.5        3) 0.75        4) 0.25
Ans: (1)
Explanation: Volume strength of H2O2 = Molarity of H2O2 × 11.2

 

18. The pH of H2O and D2O at room temperature is
       1) 7 & 7        2) 7 & 7.35        3) 7 & 6.85        4) 7 & 7.001
Ans: (2)
Explanation: pH of H2O = 7.0; pH of D2O = 7.35

 

19. Restoration of aerobic conditions to sewage wastes can be done by using
       1) more Oxygen        2) more Ozone       3) H2O2        4) Perhydrol
Ans: (3)
Explanation: H2O2 is used to treat sewage as it is environmental friendly.

 

20. 50 ml of given sample of H2O2 gives 5000 ml of Oxygen at S.T.P. The given sample is
       1) 100 volume H2O2           2) 17.9 N
       3) 30.35%                       4) all the above
Ans: (4)
Explanation: 10 volume H2O2 = 1.79 N = 3.035% 
                   100 volume H2O2 = 17.9 N = 30.35% 

 

21. The correct order of enthalpy of combustion (in KJ/ mole) of the following is
       1) H2 > LPG > CH4 > Octane (l)       2) Octane (l) > LPG > CH4 > H2
       3) LPG > H2 > Octane (l) > CH4       4) Octane (l) > H2 > LPG > CH4
Ans: (2)
Explanation: Enthalpy of combustion of Octane (l) = 5511 KJ/ mole
                            LPG = 2220 KJ/ mole
                            CH4 = 880 KJ/ mole
                            H2 (g) = 286 KJ/ mole.

 

22. Incorrect statement among the following is
       1) D2O is by-product in some fertilizer industries.
       2) H2O2 is used to manufacture sodium per borate.
       3) Perhydrol is antiseptic.
       4) NH3 is used as stabiliser for H2O2.
Ans: (4)
Explanation: Urea is added to H2O2 as a stabiliser.

 

23. Pure water can be obtained from sea water by
       1) Coagulation        2) Sedimentation       3) Evaporation        4) Reverse osmosis
Ans: (4)
Explanation: Pure water is obtained by reverse osmosis.

 

24. The meaning of hydride gap is
       1) 7, 8, 9 group elements do not form metallic hydrides.
       2) Bond length of H & metal atom.
       3) 4, 5, 6 group elements do not form metallic hydrides.
       4) Entry of elements in the gap of hydrides.
Ans: (1)
Explanation: Non formation of hydrides by 7, 8, 9 group elements is called as "Hydride gap".

 

25. Dihedral angles in H2O2 in gaseous phase and H2O2 in solid phase are respectively
       1) 110°, 111°        2) 90.2°, 111.5°       3) 111.5°, 90.2°        4) 90°, 91°
Ans: (3)
Explanation: Dihedral angle decreases when H2O2 changes its physical state from gas to solid.

Posted Date : 15-10-2020

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