Chemistry Multiple Choice Questions on “Bond Parameters”.
1. Which of the following cannot be used to measure bond lengths?
a) Spectroscopy
b) X-ray diffraction
c) Electron diffraction
d) Young’s Double-slit method
Answer: d
Clarification: The equilibrium distance between the nuclei of two bonded atoms in a molecule is known as bond length. It can be measured by spectroscopy, X-ray diffraction, and electron diffraction. Young’s double slit method is used for determining electromagnetic spectra.
2. The covalent radius in a chlorine molecule and van der Waal’s radius between chlorine molecules respectively can be ________ & _________
a) 99pm, 198pm
b) 198pm, 99pm
c) 198pm, 198pm
d) 99pm, 99m
Answer: a
Clarification: The half of the distance between two covalently bonded similar atoms in the same molecule is called covalent radius, whereas the half of the distance between two similar atoms of different molecules in a solid is known as van der Waal’s radius. Therefore covalent radius is smaller than the van der Waal’s radius.
3. What are the units of measuring the bond angle?
a) meters
b) kilograms
c) degree
d) mole
Answer: c
Clarification: The angle between two bonds from the same atom that is bonded to different atoms is called the bond angle. It expressed in the units of degree experimentally by spectroscopic methods. It depicts the shape of the molecule in a 3D dimension.
4. The bond angle between the hydrogen atoms is _________
a) 104.5°
b) 104°
c) 105.4°
d) 105°
Answer: a
Clarification: The water molecule is the V-shape, so the angle between hydrogen through oxygen is given → by 104.5°. As we know the angle between two bonds from the same atom that is bonded to different atoms is called the bond angle.
5. Strength of the bond between the two atoms can be known from bond dissociation enthalpy.
a) True
b) False
Answer: a
Clarification: Yes, it’s true. The energy that is used to break a molecule into atoms is bond dissociation enthalpy. The higher the bond dissociation energy, the stronger the bond between the atoms. So the strength of the bond between the two atoms can be known from bond dissociation enthalpy.
6. The bond enthalpy of H2O and OH are 502 KJ mol-1 and 427 KKJ mol-1. Then what is the average bond enthalpy?
a) 502 KJ mol-1
b) 464.5 KJ mol-1
c) 427 KJ mol-1
d) 75 KJ mol-1
Answer: b
Clarification: We know that H2O(g) → H(g) + OH(g); ΔH1 = 502 kJ mol-1 and OH(g) → H(g) + O(g); ΔH2 = 427 kJ mol-1. So the average bond enthalpy is given by their mean that is 427 + 502/2 = 464.5 KJ mol-1. This method is used for polyatomic molecules like water.
7. What is the bond order of CO?
a) 3
b) 2
c) 1
d) 4
Answer: a
Clarification: The number of bonds that are created between two atoms in a molecule is the bond order of that bond. The molecule carbon monoxide CO has a triple bond between the carbon and oxygen, so it’s bond order is 3.
8. All the __________ species(molecules and ions) have the same bond order.
a) isotopic
b) isoelectronic
c) isobaric
d) isoneutronic
Answer: b
Clarification: The molecules and ions that contain the same number of electrons are called isoelectronic species. They all have the same bond order. For example, the molecules and ions like N2, CO and NO+ have the bond order 3 and 14 electrons.
9. Resonance does stabilize the molecule.
a) False
b) True
Answer: b
Clarification: Resonance stabilizes the molecule as the resonance hybrid comprises of less energy than other canonical structures. Resonance is made of many structures that change frequently in molecules in order to maintain stability in the molecule.
10. Which of the following molecules may have a dipole movement?
a) N2
b) CH4
c) BeF2
d) H2O
Answer: d
Clarification: The dipole movement is given by the product of charge and the distance of separation between atoms. It is expressed in Debye units (D). For the molecules N2, CH4 and BeF2 the net dipole movement is zero as they cancel each other due to symmetry. But water molecule due to its V-shape exhibits dipole movement.