NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions


The correction factor ‘a’ to the ideal gas equation corresponds to

  • Density of the gas molecules

  • Volume of the gas molecules

  • Forces of attraction between the gas molecules

  • Electric field present between the gas molecules


Forces of attraction between the gas molecules

In the real gas equation, P + an2V2 (V-nb) = nRT van der Waal's constant, 'a' signifies intermolecular forces of attraction.


The bond dissociation energies of X2, Y2 and XY are in the ratio of 1 : 0.5: 1. ΔH for the formation of XY is –200 kJ mol–1. The bond dissociation energy of X2 will be

  • 200 kJ mol-1

  • 100 kJ mol-1

  • 400 kJ mol-1

  • 800 kJ mol-1


800 kJ mol-1

Let B.E of x2,y2 and xy are x kJ mol-1, 0.5 x kJ mol-1 and x kJ mol-1 respectively

12x2 + 12y2  xy;H = - 200 kJ mol-1H = - 200 = Σ(B.E)reactant - Σ(B.E)product = 12  x (x) +12 x (0.5)x-[1x (x)]On solving we get, B.E of X2 = x = 800 kJ mol-1


Which oxide of nitrogen is not a common pollutant introduced into the atmosphere both due to natural and human activity?

  • N2O5

  • NO2

  • NO

  • N2O



Nitrous oxide (N2O) occurs naturally in the environment.

In an automobile engine, when fuel is burnt dinitrogen and dioxygen combine to yield NO and NO2


Which of the following oxides is most acidic in nature?

  • MgO

  • BeO

  • CaO

  • BaO



In metals moving down the group metallic character increases, so basic nature increases hence most acidic will be BeO.


The correct order of atomic radii in group 13 elements is

  • B < Al < In < Ga < Tl

  • B < Al < Ga < In < Tl

  • B < Ga < Al < In < Tl

  • B < Ga < Al < Tl < In


B < Ga < Al < In < Tl

Atomic and ionic radii. Atomic and ionic radii of group 13 elements increase from top to bottom in the group. This is due to increase in the number of energy shells in each succeeding element. However, the atomic radius of gallium (Ga) is less than that of aluminium (Al).

It is due to the poor shielding of the valence electrons of Ga by the inner 3d-electrons. As a result, the effective nuclear charge of Ga is somewhat greater in magnitude than that of Al. Thus, the electrons in gallium experience the greater force of attraction by the nucleus than in aluminium. Hence the atomic size of Ga(135 pm) is slightly less than that of Al(143 pm).



Magnesium reacts with an element (X) to form an ionic compound. If the ground state electronic configuration of (X) is 1s2 2s2 2p3, the simplest formula for this compound is

  • Mg2X3

  • MgX2

  • Mg3X2

  • Mg2X



Element (X) electronic configuration

1s2 2s2 2p3

So, valency of X will be 3.
Valency of Mg is 2.
Formula of the compound formed by Mg and X
will be Mg3X2


Consider the change in oxidation state of Bromine corresponding to different emf values as shown in the diagram below :

BrO4- 1.82BrO3-1.5 VHBrO1.595Br21.0652 VBr-

Then the species undergoing disproportionation is

  • BrO3-

  • BrO4-

  • HBrO

  • Br2



Calculate Ecell° corresponding to each compound undergoing disproportionation reaction. The reaction for which Ecell° comes out +ve is spontaneous.

HBrO   Br2Eo = 1.595 V, SRP (cathode)HBrO    BrO3-Eo = - 1.5 V, SOP (anode)2HBrO   Br2 + BrO3-Ecello = SRP (cathode)- SRP (anode)= 1.595 - 1.5= 0.095 VEcell0> 0  Go < 0 [spontaneous]


Which one is a wrong statement?

  • Total orbital angular momentum of electron in 's' orbital is equal to zero

  • An orbital is designated by three quantum numbers while an electron in an atom is designated by four quantum numbers

  • The value of m for dz2 is zero

  • The electronic configuration of N atom is


The electronic configuration of N atom is

According to Hund's Rule of maximum multiplicity, the correct electronic configuration of N-atom is


Which one of the following conditions will favour maximum formation of the product in the reaction,

A2 (g) + B2 (g)       X2 (g)r H = - XkJ?

  • Low temperature and high pressure

  • Low temperature and low pressure

  • High temperature and low pressure

  • High temperature and high pressure


Low temperature and high pressure

A2 (g)+ B2 (g)   X2 (g);  H = - xkJ

On increasing pressure equilibrium shift in a direction where number of moles decreases i.e. forward direction.

On decreasing temperature, equilibrium shift n exothermic direction i.e., forward direction.

So high pressure and lower temperature favour maximum formation of product.


Which of the following molecules represents the order of hybridisation sp2, sp2, sp, sp from left to right atoms?

  • HC≡C-C≡CH

  • CH2=CH-C≡CH

  • CH3-CH=CH-CH3

  • CH2=CH-CH=CH2



CH2 sp2=CHsp2 - Csp CspH