Question Set B

CBSE 11th Chemistry Chemical Bonding and Molecular Structure Model Questions Papers Study Material - QB365

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Questions:

Multiple Choice Question

45 x 1 = 45

Consider the reactions given below. On the basis of these reactions find out which of the algebric relations given in options (a) to (d) is correct?
(i) \( \mathrm{C}(g)+4 \mathrm{H}(g) \longrightarrow \mathrm{CH}_{4}(g) ; \Delta_{r} H=x \mathrm{~kJ} \mathrm{~mol}^{-1} \)
(ii)\( \text { C(graphite, } s)+2 \mathrm{H}_{2}(g) \longrightarrow \mathrm{CH}_{4}(g) ; \Delta_{r} H \doteq y \mathrm{~kJ} \mathrm{~mol}^{-1} \)

(a)

x = y

(b)

x = 2y

(c)

x > y

(d)

x < y

The spontaneity means, having the potential to proceed without the assistance of external agency. The processes which occur spontaneously are______.

(a)

flow of heat from colder to warmer body.

(b)

gas in a container contracting into one corner.

(c)

gas expanding to fill the available volume.

(d)

burning carbon in oxygen to give carbon dioxide.

If the bond energies of H-H, Br-Br and H-Br are 433, 192 and 364 kJ mol^-1, respectively, then \(\Delta \mathbf{H}^{\circ}\) for the reaction. \(\mathbf{H}_{2}(g)+\operatorname{Br}(g) \longrightarrow 2 \mathrm{HBr}(g) \text { is }\) ______.

(a)

-261 kJ

(b)

-103 kJ

(c)

+261 kJ

(d)

-1031 kJ

The enthalpy of vapourisation of a liquid is 30 kJ mol^-1 and enthalpy of vapourisation is 75 J mol^-1. The boiling point of the liquid at 1 atm is ______.

(a)

250 K

(b)

400 K

(c)

450 K

(d)

600 K

A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy in Joule's will be ______.

(a)

- 500 J

(b)

- 506 J

(c)

+ 505 J

(d)

1136.25 J

CO is isoelectronic with ______.

(a)

NO⁺

(b)

N₂

(c)

SnCl₂

(d)

\(\mathrm{NO}_{2}^{-}\)

Which of the following isoelectronic and isostructural

(a)

\( \mathrm{CO}_{3}^{2-}, \mathrm{NO}_{3}^{0-} \)

(b)

\( \mathrm{ClO}_{3}^{-}, \mathrm{CO}_{3}^{2-} \)

(c)

\(\mathrm{SO}_{3}^{2-}, \mathrm{NO}_{3}^{-} \)

(d)

\(\mathrm{ClO}_{3}^{-}, \mathrm{SO}_{3}^{2-}\)

Which of the following molecules aU bonds not equal?

(a)

PCl₅

(b)

SF₆

(c)

BF₃

(d)

AIF₃

Which of the following is an electron deficient molecule?

(a)

C₂H₆

(b)

B₂H₆

(c)

SiH₄

(d)

PH₃

10.

The correct order of dipole moment is ______.

(a)

CH₄< NF₃ < NH3 < H₂O

(b)

NF₃ < CH₄ < NH₃ < H₂O

(c)

CH₄ < NH₃ < NF₃ < H₂O

(d)

< H₂O < NH₃ < NF₃ < CH₄

11.

Which of the following, is correct when decrease in entropy has been taken place?

(a)

Temperature of a crystalline solid is raised from 0 K to 115 K

(b)

A liquid crystallises into a solid

(c)

\(2 \mathrm{NaHCO}_{3}(s) \stackrel{\Delta}{\longrightarrow} \mathrm{Na}_{2} \mathrm{CO}_{3}(s)+\mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)\)

(d)

\(\mathrm{H}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{H}(\mathrm{g})\)

12.

Which of the following properties is the measure of the degree of randomness or disorder in the system?

(a)

Entropy

(b)

Enthalpy

(c)

Internal energy

(d)

None of these

13.

Maximum entropy will be in which of the following?

(a)

Ice

(b)

liquid water

(c)

snow

(d)

water vapour

14.

Lattice enthalpies are determined by ______.

(a)

Born-Haber cycle

(b)

Hess' law

(c)

lattice cycle

(d)

None of these

15.

Calculate the difference between C_p and C_v for 10 moles of an ideal gas.

(a)

83.14 J

(b)

8.314 J

(c)

831.4 J

(d)

0.831 J

16.

A reaction, A + B ⟶ 7 C + D + q is found to have a positive entorpy change. The reaction will be ______.

(a)

possible at high temperature

(b)

possible only at low temperature

(c)

not possible at any temperature

(d)

possible at any temperature

17.

For both reversible and irreversible expansion of an ideal gas, under isothermal condition, ______.

(a)

\(\Delta U=0, \Delta S_{\text {total }} \neq 0\)

(b)

\(\Delta U \neq 0, \Delta S_{\text {total }}=0\)

(c)

\(\Delta U \neq 0, \Delta S_{\text {total }}=0\)

(d)

\(\Delta U \neq 0, \Delta S_{\text {total }} \neq 0\)

18.

The sign of ΔG for a spontaneous and non-spontaneous process respectively are ______.

(a)

positive and negative

(b)

negative and positive

(c)

zero and positive

(d)

positive and zero

19.

Select the incorrect expression from the following

(a)

\(\Delta S_{\text {total }}=\Delta S_{\text {system }}+\Delta S_{\text {surr }}\)

(b)

\(\Delta S_{\text {surr }}=\frac{\Delta H_{\text {surr }}}{T}=-\frac{\Delta H_{\text {sys }}}{T}\)

(c)

\(\Delta S_{\text {total }}<0 \text { (spontaneous process) }\)

(d)

\(\Delta G=\Delta H-T \Delta S\)

20.

Which one of the following reaction has ΔS^o greater than zero?

(a)

\(\mathrm{CaO}+\mathrm{CO}_{2}(g) \rightleftharpoons \mathrm{CaCO}_{3}(s)\)

(b)

\(\mathrm{NaCl}(a q) \rightleftharpoons \mathrm{NaCl}(s)\)

(c)

\(\mathrm{NaNO}_{3}(s) \rightleftharpoons \mathrm{Na}^{+}(a q)+\mathrm{NO}_{3}^{-}(s q)\)

(d)

\(\mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NH}_{3}(\mathrm{~g})\)

21.

The enthalpy change when one mole of solute dissolves in a specified amount of solvent is called ______.

(a)

enthalpy of dilution

(b)

enthalpy of solution

(c)

enthalpy of association

(d)

enthalpy of dissociation

22.

For the reaction, \(\mathrm{NaCl}(s) \longrightarrow \mathrm{Na}^{+}(g)+\mathrm{Cl}^{-}(g)\) Identify the enthalpy involved in the above reaction ______.

(a)

enthalpy of hydration

(b)

lattice enthalpy

(c)

enthalpy of solution

(d)

enthalpy of dissociation

23.

Enthalpy change for the reaction \(4 \mathrm{H}(g) \longrightarrow 2 \mathrm{H}_{2}(g) \text { is }-869.6 \mathrm{~kJ}\) The dissociation energy of H-H bond is ______.

(a)

-869.6 kJ

(b)

+434.8 KJ

(c)

+217.4 kJ

(d)

-434.8 kJ

24.

In the given reaction, \(\mathrm{H}_{2}(g) \longrightarrow 2 \mathrm{H}(g) ; \quad \Delta H=435.0 \mathrm{~kJ} \mathrm{~mol}^{-1}\) The enthalpy change is known as ______.

(a)

enthalpy of formation

(b)

enthalpy of atomisation

(c)

bond dissociation enthalpy

(d)

Both (b) and (c)

25.

For the given reaction, \(\mathrm{CH}_{4}(g)+2 \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(l)\) the correct expression for \(\Delta_{r} H \text { is }\) ______.

(a)

\( {\left[H_{m}\left(\mathrm{CO}_{2}, g\right)+2 H_{m}\left(\mathrm{O}_{2}, g\right)\right]-\left[2 H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right.} \left.+H_{m}\left(\mathrm{CH}_{4}, g\right)\right] \)

(b)

\( {\left[2 H_{m}\left(\mathrm{O}_{2}, g\right)+H_{m}\left(\mathrm{CH}_{4}, g\right)\right]-\left[H_{m}\left(\mathrm{CO}_{2}, g\right)\right.} \left.+2 H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right] \)

(c)

\( {\left[H_{m}\left(\mathrm{CO}_{2}, g\right)+2 H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right]-\left[H_{m}\left(\mathrm{CH}_{4}, g\right)\right.} \left.+2 H_{m}\left(\mathrm{O}_{2}, g\right)\right] \)

(d)

\( {\left[H_{m}\left(\mathrm{CO}_{2}, g\right)+H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right]-\left[H_{m}\left(\mathrm{CH}_{4}, \mathrm{~g}\right)\right.} \left.+2 H_{m}\left(\mathrm{O}_{2}, g\right)\right] \)

26.

The enthalpies of elements in their standard states are taken as zero. The enthalpy of formation of a compound______.

(a)

is always negative

(b)

is always positive

(c)

may be positive or negative

(d)

is never negative

27.

For the reaction \(\mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g) \rightleftharpoons 2 \mathrm{NH}_{3}(g) ; \Delta H\) is ______.

(a)

\(\Delta U-2 R T\)

(b)

\(\Delta U-R T\)

(c)

\(\Delta U+R T\)

(d)

\(\Delta U+2 R T\)

28.

Which of the following combinations of atomic orbitals will give antibonding n-molecular orbital (assume Z-axis as internuclear axis).

(a)

\(2 s+2 p_{z}\)

(b)

\(2 p_{y}+2 p_{y}\)

(c)

\(2 p_{x}-2 p_{x}\)

(d)

\(2 p_{z}-2 p_{z}\)

29.

The boiling point of a substance increases with increase in ______.

(a)

intermolecular hydrogen bonding

(b)

intramolecular hydrogen bonding

(c)

molecular mass

(d)

Both (a) and (c)

30.

The correct decreasing order of the boiling points of given compounds is ______.

(a)

HF > H₂O > NH₃

(b)

H₂O > HF > NH₃

(c)

NH₃> HF> H₂O

(d)

NH₃ > H₂O > HF

31.

In which of the following substances will hydrogen bond be strongest?

(a)

HCI

(b)

H₂O

(c)

(d)

H₂S

32.

If N_b is the number of electrons occupying bonding orbitals and N_a the number of electrons occupying the antibonding orbitals, then the molecule will be stable if ______.

(a)

N_b > N_a

(b)

N_b < N_a

(c)

N_b = N_a

(d)

N_b < N_a

33.

Which of the following angle corresponds to sp² hybridisation?

(a)

90^o

(b)

120^o

(c)

180^o

(d)

109^o

34.

The above potential energy curve is given for the formation of H₂molecule as a function of internuclear distance of H-atoms. At what point in the curve H₂ is found in the most stable state?

(a)

(b)

(c)

(d)

35.

The valence bond theory explains the shape, the formation and directional properties of bonds in polyatomic molecules like CH₄, NH₃and H₂O etc, in terms of ______.

(a)

overlapping of atomic orbitals

(b)

hybridisation of atomic orbitals

(c)

Both (a) and (b)

(d)

None of the above

36.

VBTtheory is based on the ______.

(a)

knowledge of atomic orbitals and electronic configuration of elements

(b)

overlapping criteria and the hybridisation of atomic orbitals

(c)

the principles of variation and superposition

(d)

All of the above

37.

Sidgwick and Powell proposed the VSEPR theory which was further developed and refined by ______.

(a)

Johann Dobereiner

(b)

Werner Heisenberg

(c)

Nyholm and Gillespie

(d)

Neils Bohr

38.

Which theory can be best understood by considering the formation of the chlorine molecule, C1₂?

(a)

Lewis theory

(b)

Langmuir theory

(c)

Lewis-Langmuir theory

(d)

Kossel-Lewis theory

39.

The product of the magnitude of the charge and the distance between the centres of positive and negative charge is called ______.

(a)

charge ratio

(b)

dipole moment

(c)

current flow

(d)

magnetic moment

40.

Lewis postulated that atoms achieve the stable octet when they are linked by ______.

(a)

ionic bonds

(b)

covalent bonds

(c)

coordinate bonds

(d)

chemical bonds

41.

For an endothermic reaction ______.

(a)

\(\Delta\)H is-ve

(b)

\(\Delta\)H is+ve

(c)

\(\Delta\)H is zero

(d)

none of these

42.

For a cyclic process, the change in internal energy of the system is ______.

(a)

always +ve

(b)

equal to zero

(c)

always -ve

(d)

none of the above

43.

Thermodynamics is applicable to ______.

(a)

macroscopic system only

(b)

microsopic system only

(c)

homogeneous system only

(d)

heterogeneous system only

44.

The molecule Ne₂ does not exist because ______.

(a)

N_b > N_a

(b)

N_b = N_a

(c)

N_b < N_a

(d)

None of these

45.

A molecule or ion is stable if: ______.

(a)

N_b = N_a

(b)

N_b < N_a

(c)

N_a < N_b

(d)

N_a - N_b =+ve

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Answers Key:

Multiple Choice Question

45 x 1 = 45

(d)
burning carbon in oxygen to give carbon dioxide.

(b)
-103 kJ

(b)
400 K

(b)
- 506 J

(a)
NO⁺

(a)
\( \mathrm{CO}_{3}^{2-}, \mathrm{NO}_{3}^{0-} \)

(a)
PCl₅

10.

(a)
CH₄< NF₃ < NH3 < H₂O

11.

(b)
A liquid crystallises into a solid

12.

(a)
Entropy

13.

(d)
water vapour

14.

(a)
Born-Haber cycle

15.

(a)
83.14 J

16.

(d)
possible at any temperature

17.

(a)
\(\Delta U=0, \Delta S_{\text {total }} \neq 0\)

18.

(b)
negative and positive

19.

20.

21.

(b)
enthalpy of solution

22.

(b)
lattice enthalpy

23.

(b)
+434.8 KJ

24.

(b)
enthalpy of atomisation

25.

(c)
\( {\left[H_{m}\left(\mathrm{CO}_{2}, g\right)+2 H_{m}\left(\mathrm{H}_{2} \mathrm{O}, l\right)\right]-\left[H_{m}\left(\mathrm{CH}_{4}, g\right)\right.} \left.+2 H_{m}\left(\mathrm{O}_{2}, g\right)\right] \)

26.

27.