Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

The cooling in refrigerator is due to :

  • the reaction of the refrigerator gas

  • the expansion of ice

  • the expansion of the gas in the refrigerator

  • the work of the compressor


C.

the expansion of the gas in the refrigerator

This is based on Joule-Thomson effect.


2.

A precipitate of AgCl is formed when equal volumes of the following are mixed :

[Ksp for AgCl = 10-10]

  • 10-4 M AgNO3 and 10-7 M HCl

  • 10-5 M AgNO3 and 10-6 M HCl

  • 10-5 M AgNO3 and 10-4 M HCl

  • 10-6 M AgNO3 and 10-6 M HCl


B.

10-5 M AgNO3 and 10-6 M HCl

For the precipitation of an electrolyte, it is necessary that the ionic product must exceed its solubility product. A precipitate of AgCl is formed when equal volumes of 10-5 M AgNOand 10-5 M HCl are mixed, because ionic product will be 10-9 which is greater than Ksp (10-10).


3.

Pick out the incorrect statement from the following :

  • sp hybrid orbitals are equivalent and are at an angle of 180° with each other

  • sp2 hybrid orbitals are equivalent and bond angle between any two of them is 120°

  • sp3dhybrid orbitals are equivalent and are oriented towards corners of a regular octahedron

  • dsp2 hybrid orbitals are equivalent with a bond angle of 90° between the two atoms


D.

dsp2 hybrid orbitals are equivalent with a bond angle of 90° between the two atoms

Angle between any two dsp2 hybrid orbitals can be 90° or 180°


4.

An evacuated glass vessel weighs 50 g when empty, 144.0 g when filled with a liquid of density 0.47 g mL-1 and 50.5 g when filled with an ideal gas at 760 mm Hg and 300 K. The molar mass of the ideal gas is :

[R = 0.0821 L atm K-1 mol-1]

  • 61.575

  • 130.98

  • 123.75

  • 47.87


A.

61.575

Weight of empty glass vessel = 50 g
Weight of glass vessel filled with liquid = 144.0 g

Weight of liquid = 144- 50 = 94g
Density of liquid= 0.47 gmL-1

Volume of liquid = 940.47 = 200mL = 0.2L

Mass of glass vessel filled with gas= 50.5 g

Mass of gas (m) = 50.5- 50 = 0.5 g

By using ideal gas equation ,

pV = mWRT

where , p= 760 mm, Hg= 1atm ,
            V = 0.2 L , T = 300K ,
and      R = 0.0821 L atm K-1 mol-1

Molar mass (M) =mRTpV

0.5 × 0.0821 × 3001 × 0.2

= 61.575g mol-1


5.

In an exothermic equilibrium ,

A + 3B  AB3

all the reactants and products are in gaseous state. The formation of AB3 is favoured at :

  • low temperature and low pressure

  • low temperature and high pressure

  • high temperature and high pressure

  • high temperature and low pressure


B.

low temperature and high pressure

The given reaction is exothermic (ΔH < 0) and accompanied by decrease in the number of moles. Hence, it will be favoured by low temperature and high pressure.


6.

A bivalent metal has an equivalent mass of 32. The molecular mass of the metal nitrate is :

  • 182

  • 168

  • 192

  • 188


D.

188

Atomic mass of the metal = 32 x 2 = 64

Formula of metal nitrate= M(NO3)2

 Molecular mass = 64 + (14 + 3 x 16) x 2 = 188


7.

20 mL of 0.5 N HCl and 35 mL of 0.1 N NaOH are mixed. The resulting solution will :

  • be neutral

  • be basic

  • turn phenolphthalein solution pink

  • turn methyl orange red


C.

turn phenolphthalein solution pink

For 20 ml of 0.5 N HCl
     N1V1 = 0.5 x 20 = 10
For 35 ml of 0.1 NaOH
     N2V2 = 0.1x 35= 3.5

 N1V1 > N2V2

So!ution will be acidic in nature.
Due to acidic nature of solution, the colour of phenolphthalein becomes pink.


8.

The line spectrum of He+ ion will resemble that of :

  • hydrogen atom

  • Li+ ion

  • helium atom

  • lithium atom


A.

hydrogen atom

As hydrogen atom and He+ ion both have only one electron, hence the line spectrum of both will resemble.


9.

A body of mass x kg is moving with a velocity of 100 ms-1. Its de-Broglie wavelength is 6.62 x 10-35 m. Hence, x is :

[h = 6.62 x 10-34Js]

  • 0.1 Kg

  • 0.25 Kg

  • 0.15 Kg

  • 0.2 Kg


A.

0.1 Kg

λ = hmv

 m = 6.62 × 10-346.62 × 10-35 × 100

= 0.1 Kg


10.

0.5 mole of each of H2 , SO2 and CH4 are kept in a container. A hole was made in the container . After 3h , the order of partial pressures in the container will be :

  • pSO2 > pH2 > pCH4

  • pSO2 > PCH4 > pH2

  • pH2 > pSO2 > pCH4

  • pH2 > pCH4 > pSO2


B.

pSO2 > PCH4 > pH2

Rate of diffusion  1molecular mass

 Order of diffusion H2 > CH4 > SO2

and amount left is in the order :
       SO2 > CH4 > H2

Hence, order of partial pressure is
       pSO2 > pCH4 > pH2