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NEET Chemistry Solved Question Paper 2018

Multiple Choice Questions

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

$B r O_{4}^{-} \overset{1.82}{\to} B r O_{3}^{-} \overset{1.5 V}{\to} H B r O \overset{1.595}{\to} B r_{2} \overset{1.0652 V}{\to} B r^{-}$

Then the species undergoing disproportionation is

$B r O_{3}^{-}$
$B r O_{4}^{-}$
HBrO
Br₂

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

$A_{2} (g) + B_{2} (g) \overset{}{⇋} X_{2} (g) ∆_{r} H = - X k J ?$

Low temperature and high pressure
Low temperature and low pressure
High temperature and low pressure
High temperature and high pressure

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

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

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 d_z2 is zero
The electronic configuration of N atom is

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

7.
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).