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Free download in PDF CBSE Class 12 Chemistry Objective Type Questions & Answers. Here Gkseries provide Chemistry Solve Questions and Answers for CBSE Class 12 Students.
(21)
An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because _________ .
[A]
it gains water due to osmosis.
[B]
it loses water due to reverse osmosis.
[C]
it gains water due to reverse osmosis.
[D]
it loses water due to osmosis.
Answer: it loses water due to reverse osmosis.
(22)
In comparison to a 0.01 M solution of glucose, the depression in freezing point of a 0.01 M MgCl2 solution is _________ .
[A]
the same
[B]
about twice
[C]
about three times
[D]
about six times
Answer: about three times
(23)
Which of the following aqueous solutions should have the highest boiling point?
[A]
1.0 M NaOH
[B]
1.0 M Na2SO4
[C]
1.0 M NH4NO3
[D]
1.0 M KNO3
(24)
Considering the formation, breaking and strength of hydrogen bond, predict which of the following mixtures will show a positive deviation from Raoult’s law?
[A]
Methanol and acetone.
[B]
Phenol and aniline.
[C]
Chloroform and acetone.
[D]
Nitric acid and water.
Answer: Methanol and acetone.
(25)
Low concentration of oxygen in the blood and tissues of people living at high altitude is due to _________ .
[A]
low temperature
[B]
low atmospheric pressure
[C]
high atmospheric pressure
[D]
both low temperature and high atmospheric pressure
Answer: low atmospheric pressure
(26)
The number of moles of NaCl in 3 litres of 3M solution is
(27)
The molality of pure water is
[A]
60.5
[B]
55.5
[C]
50.5
[D]
18
(28)
If E°Fe2+/Fe = -0.441 V and E°Fe2+/Fe2+ = 0.771 V, the standard EMF of the reaction,
Fe + 2Fe3+ → 3Fe2+ will be
[A]
1.212 V
[B]
1.653 V
[C]
0.111 V
[D]
0.330 V
(29)
The reaction, 3ClO– (aq) → ClO3 (aq) + 2Cl– (aq) is an example of
[A]
Oxidation reaction
[B]
Reduction reaction
[C]
Disproportionation reaction
[D]
Decomposition reaction
Answer: Disproportionation reaction
(30)
NH4NC>3 is used in salt bridge because
[A]
it forms a jelly like material with agar-agar.
[B]
it is a weak electrolyte.
[C]
it is a good conductor of electricity.
[D]
the transport number of NH4+ and NO3– ions are almost equal.
Answer: the transport number of NH4+ and NO3– ions are almost equal.
31
limiting molar conductivity of Ca2+ and Cl– are 119.0 and 76.3 S cm2 mol-1, then the value of limiting molar conductivity of CaCl2 will be
[A]
195.3 S cm2 mol-1
[B]
271.6 S cm2 mol-1
[C]
43.3 S cm2 mol-1
[D]
314.3 S cm2 mol-1.
Answer: 271.6 S cm2 mol-1
32
The charge required for the reduction of 1 mol of MnO2– to MnO2 is
[A]
1 F
[B]
3 F
[C]
6 F
[D]
5 F
33
Λ of M/32 solution of weak acid is 8 S cm2 mol-1 and limiting molar conductivity is 400 S cm2 mol1. Ka for acid is
[A]
1.25 × 10-6
[B]
6.25× 10-4
[C]
1.25 × 10-4
[D]
1.25 × 10-5
34
While charging the lead storage battery _________ .
[A]
PbSO4 anode is reduced to Pb.
[B]
PbSO4 cathode is reduced to Pb.
[C]
PbSO4 cathode is oxidised to Pb.
[D]
PbSO4 anode is oxidised to PbO2.
Answer: PbSO4 anode is reduced to Pb.
35
A conductivity cell containing electrodes made up of
[A]
Gold
[B]
Silver
[C]
Platinised platinum
[D]
Copper
Answer: Platinised platinum
36
Ag+(aq) + e– → Ag(s) E° = + 0.80 V
Fe2+(aq)+ + 2e– → Fe(s) E° = – 0.44 V
What is emf of
Fe(s) + 2Ag+(aq) → Fe2+(aq) + 2Ag(s)
[A]
1.16 V
[B]
1.24 V
[C]
2.04 V
[D]
-1.16 V
37
A new galvanic cell of E^u more than E°dl of Daniel cell is connected to Daniel cell in a manner that new cell gives electrons to cathode, what will happen
[A]
Ecell will increase
[B]
Ecell will decrease
[C]
No change will take place
[D]
Daniel cell will work as electrolytic cell where Zn will be deposite on zinc rod and copper will dissolve from copper rod.
Answer: Ecell will decrease
38
The emf of the cell:
Ni / Ni2+ (1.0 M) // Au3+ (1.0 M) / Au (E° = -0.25 V for Ni2+/Ni; E° = 1.5 V for Au3+/Au) is
[A]
1.25 V
[B]
-1.25 V
[C]
1.75 V
[D]
2.0 V
39
The half life period of first order reaction is 1386 seconds. The specific rate constant of the reaction is
[A]
0.5 × 10-3 s-1
[B]
5.0 × 10-3 s-1
[C]
0.5 × 10-2 s-1
[D]
5.0 × 10-2 s-1
40
The rate constant of a reaction A → B is 0.6 × 103 mole per second. If the concentration of [A] is 5 M, then what will be concentration of [B] after 20 months?
[A]
3.60 M
[B]
0.36 M
[C]
0.72 M
[D]
None of these
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