Chemical Bonding and Molecular Structure Questions and Answers Part-8

1. Which of the following has zero dipole moment?
a) ClF
b) \[PCI_{3}\]
c) \[SiF_{4}\]
d) \[CFCI_{3}\]

Answer: c
Explanation: In \[SiF_{4}\]   DM = zero due to symmetrical structure.

2. Dipole moment is shown by
a) 1, 4-dichlorobenzene
b) cis 1,2-dichlorobenzene
c) trans 1, 3-dichlorobenzene
d) trans 2, 3-dichloro -2- butene

Answer: b

3. Which one of the following molecules will have unequal M – F bond lengths ?
a) \[NF_{3}\]
b) \[BF_{3}\]
c) \[PF_{5}\]
d) \[SF_{4}\]

Answer: c

4. The bond length in LiF will be
a) less than that of NaF
b) equal to that of KF
c) more than that of KF
d) equal to that of NaF

Answer: a
Explanation: It is due to small size of Li compared to size of Na and K

5. Which has the least bond angle ?
a) \[NH_{3}\]
b) \[BeF_{2}\]
c) \[H_{2}O\]
d) \[CH_{4}\]

Answer: c
Explanation: Bond angles NH3 (107.5º); BeF2 (180º); H2O (104.5º) and CH4 (109º28’)

6.The correct sequence of decrease in the bond angles of the following hydrides is
a) \[NH_{3}>PH_{3}>AsH_{3}>SbH_{3}\]
b) \[NH_{3}>AsH_{3}>PH_{3}>SbH_{3}\]
c) \[SbH_{3}>AsH_{3}>PH_{3}>NH_{3}\]
d) \[PH_{3}>NH_{3}>AsH_{3}>SbH_{3}\]

Answer: a

7. The sulphate of a metal has the formula \[M_{2}\left(SO_{4}\right)_{3}\] The formula of its phosphate will be
a) \[M\left(HPO_{4}\right)_{2}\]
b) \[M_{3}\left(PO_{4}\right)_{2}\]
c) \[M_{2}\left(PO_{4}\right)_{3}\]
d) \[MPO_{4}\]

Answer: d
Explanation: \[M_2^{+6}\left(SO_{4}\right)_{3}^{-6}\]   Here metal atom is trivalent. Hence formula for phosphate will be \[MPO_{4}\]

8. KF combines with HF to form \[KHF_{2}\]  . The compound contains the species
a) \[K^{+},F^{-}and H^{+}\]
b) \[K^{+},F^{-} and HF\]
c) \[K^{+}, and \left[HF_{2}\right]^{-}\]
d) \[\left[KHF\right]^{+} and F_{2}\]

Answer: c
Explanation: Since F form H-bond \[\left[HF_{2}\right]^{-}\]   exists. Therefore KHF2 gives K+ + \[HF_{2}^{-}\]

9. Which of the following molecular orbitals has two nodal planes ?
a) \[\sigma 2s\]
b) \[\pi2p_{y}\]
c) \[\pi*2p_{y}\]
d) \[\sigma*2p_{x}\]

Answer: c

10. The electronic configuration of metal M is 1s2 2s2 2p6 3s1. The formula of its oxide will be
a) MO
b) \[M_{2}O\]
c) \[SO_{3}\]
d) All of these

Answer: b
Explanation: Electronic configuration reveals it is monovalent (in fact Na) hence its oxide will be M2O.