Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

The RMS velocity of CO gas molecules at 27°C is approximately 1000 m/s. For N2 molecules at 600 K, the RMS velocity is approximately

  • 2000 m/s

  • 1414 m/s

  • 1000 m/s

  • 1500 m/s


B.

1414 m/s

Given - (vrms)co = 1000 m/s

(Temp)co = 27°C

(Temp)N2 = 600 K

As the formula =vrms3RTM

By putting the values, we get

vrmscocrmsN2    = 3R3R × TCOMCO × MN2TN2 1000vrms        = 30028 × 28600 = 12or, (vrms)N2 = 1000 × 1.414                  = 1414 m/s


2.

Cold ferrous sulphate solution on absorption of NO develops brown colour due to the formation of

  • paramagnetic [Fe(H2O)5(NO)] SO4

  • diamagnetic [Fe(H2O)5(N3)] SO4

  • paramagnetic [Fe(H2O)5(NO3)][SO4]2

  • diamagnetic [Fe(H2O)4 (SO4)]NO3


A.

paramagnetic [Fe(H2O)5(NO)] SO4

Cold ferrous sulphate or FeSO4 solution on absorption of NO develops brown colour due to the formation of [Fe(H2O)5(NO)]SO4. It can be expressed as-

FeSO4 + NO + 5H2O → [Fe(H2O)5(NO)]SO4

[Fe(H2O)5(NO)]SO4 is a brown ring complex. It has 3.89 BM magnetic moment and has 3 unpaired electrons.


3.

The dispersed phase and dispersion medium of fog respectively are

  • solid, liquid

  • liquid, liquid

  • liquid, gas

  • gas, liquid


C.

liquid, gas

The dispersed phase in fog is liquid and dispersion medium in fog is gas.


4.

A gas can be liquefied at temperature T and pressure p provided

  • T = Tc and p < pc

  • T < Tc and p > pc

  • T > Tc and p > pc

  • T > Tc and p < pc


B.

T < Tc and p > pc

A gas can be liquefied at temperature T, when it is lower than critical temperature, Tc and pressure p is greater than critical pressure. Hence, T < Tc and p > pc·


5.

The decreasing order of basic character of K2O, BaO, CaO and MgO is

  • K2O > BaO > CaO > MgO

  • K2O > CaO > BaO > MgO

  • MgO > BaO > CaO > K2O

  • MgO > CaO > BaO > K2O


A.

K2O > BaO > CaO > MgO

The order of basic character, on the basis of electropositivity is K2O > BaO > CaO > MgO.


6.

For the reaction,
2SO2 (g) + O2 (g) 2SO3 (g) at 300 K, the value of G° is -690.9 R. The equilibrium constant value for the reaction at that temperature is (R is gas constant)

  • 10 atm-1

  • 10 atm

  • 10

  • 1


A.

10 atm-1

For the given reaction, 

2SO2 (g) + O2 (g)  2SO3 (g)

Given,

      G° = -690.9R, T = 300 K

From the formula, 

      G° = -RT ln K

-690.9 R = -R × 300 × ln K

or     ln K = 690.9300 = 2.303

or 2.303 log K = 2.303

or        K = 101 = 10

Unit of K = (atm)n = (atm)2-3 = (atm)-1

       K = 10 atm-1


7.

Consider the following salts : NaCl, HgCl2, Hg2Cl2, CuCl2, CuCl and AgCl. Identify the correct set of insoluble salts in water.

  • Hg2Cl2, CuCl, AgCl

  • Hg2Cl, CuCl, AgCl

  • Hg2Cl2, CuCl2, AgCl

  • Hg2Cl2, CuCl, NaCl


A.

Hg2Cl2, CuCl, AgCl

Salts such as NaCl, HgCl2, CuCl2 are soluble in water while salts such as Hg2Cl2, CuCl and AgCl are insoluble in water.


8.

The atomic number of cerium (Ce) is 58. The correct electronic configuration of Ce3+ ion is.

  • [Xe] 4f1

  • [Kr] 4f1

  • [Xe] 4f13

  • [Kr] 4d1


A.

[Xe] 4f1

Atomic number of Cerium = 58

Electronic configuration of Ce = [Xe] 4f2 5d0 6s2

Electronic configuration of Ce3+ = [Xe] 4f1


9.

At a certain temperature, the value of the slope of the plot of osmotic pressure (π) against concentration (C in molL-1) of a certain polymer solution is 291R. The temperature at which osmotic pressure is measured, is (R is gas constant) 

  • 271°C

  • 18°C

  • 564 K

  • 18 K


B.

18°C

The temperaure at which osmotic pressure is measured is, 18°C. In the given figure,

Slope, RT = 291 R or T = 291 K

Therefore, 291 - 273 = 18°C.


10.

The number of lone pairs of electrons on the central atoms of H2O, SnCl2, PCl3 an XeF2 respectively are

  • 2, 1, 1, 3

  • 2, 2, 1, 3

  • 3, 1, 1, 2

  • 2, 1, 2, 3


A.

2, 1, 1, 3

The number of lone pairs of electrons on the central atoms of H2O, SnCl2, PCl3 and XeF2 are 2, 1, 1 and 3 respectively.

 Number of lone pairs = 2

 Number of lone pairs = 1

 Number of lone pairs = 1

 Number of lone pair = 1