Topic: UNIT 10: Chemical bonding (Test 2)



Topic: UNIT 10: Chemical bonding
Q.1
Which of the following is electron deficient?
A. PH3
B. (CH3)2
C. BH3
D. NH3
Answer : Option C
Explaination / Solution:

- electron rich,

CH3 – CH3 – Covalent neutral molecule.

BH3 - electron deficient


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Q.2
Which of the following molecule contain no л bond?
A. SO2
B. NO2
C. CO2
D. H2O
Answer : Option D
Explaination / Solution:


water contain only σ bonds and no π bonds option


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Q.3
The ratio of number of sigma (σ) and pi (л) bonds in 2- butynal is
A. 8/3
B. 5/3
C. 8/2
D. 9/2
Answer : Option A
Explaination / Solution:


2-butynal

no. of σ bonds = 8[4C-H;,3C-C;1C-O]

no. of π bonds = 3[2C-C; 1C-O]

ratio=8/3


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Q.4
Which one of the following is the likely bond angles of sulphur tetrafluoride molecule?
A. 120º,80 º
B. 109 º.28
C. 90 º
D. 89 º,117 º
Answer : Option D
Explaination / Solution:


Normal bond angle in regular trigonal bipyramidal are 90º and 120 º

due to l.p - b.p repulsion, bond angle reduced 89 º, 117 º


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Q.5

Assertion: Oxygen molecule is paramagnetic.

Reason : It has two unpaired electron in its bonding molecular orbital

A. both assertion and reason are true and reason is the correct explanation of assertion
B. both assertion and reason are true but reason is not the correct explanation of assertion
C. assertion is true but reason is false
D. Both assertion and reason are false
Answer : Option C
Explaination / Solution:

Correct Statement :

Oxygen molecule is paramagnetic Correct Reason

It has two unpaired electron in its antibond-ing molecular orbital.

Option (c) assertion true and reason false.


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Q.6
According to Valence bond theory, a bond between two atoms is formed when
A. fully filled atomic orbitals overlap
B. half filled atomic orbitals overlap
C. non- bonding atomic orbitals overlap
D. empty atomic orbitals overlap
Answer : Option B
Explaination / Solution:

two half filled orbitals overlap.

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Q.7
In ClF3 ,NF3 and BF3 molecules the chlorine, nitrogen and boron atoms are
A. sp3 hybridised
B. sp3 ,sp3 and sp2 respectively
C. sp2 hybridised
D. sp3d, sp3 and sp hybridised respectively
Answer : Option D
Explaination / Solution:

ClF3 – Sp3d hybridisation

NF3 - Sp3 hybridisation

BF3 - Sp2 hybridisation


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Q.8
When one s and three p orbitals hybridise,
A. four equvivalent orbitals at 90º to each other will be formed
B. four equvivalent orbitals at 109 º 28' to each other will be formed.
C. four equivalent orbitals, that are lying the same plane will be formed
D. none of these
Answer : Option B
Explaination / Solution:

Option (b) is correct Sp3 hybridisation.

Oribital geometry tetrahedron, bond angle 109º28'    


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Q.9
Which of these represents the correct order of their increasing bond order.
A. C2 < C22- < O22- < O2
B. C2 2- < C2 + < O2 < O22-
C. O22- < O2 < C2 2- < C2 +
D. O22- < C2 +< O2 < C22-
Answer : Option D
Explaination / Solution:



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Q.10
Hybridisation of central atom in PCl5 involves the mixing of orbitals.
A. s, px, py, dx2 , dx2-y2
B. s, px . py, pxy . dx2-y2
C. s, px , py , pz , dx2-y2
D. s, px , py , dxy , dx2-y2
Answer : Option C
Explaination / Solution:

PCl5 – Sp3d hybridization

S, Px , Py , Pz  and dx2 y2


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