This set of Ceramics Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Covalent Bonding in Ceramics”.
1. Which of the following does not have a covalent bond?
a) Si-O
b) Al-O
c) C-C
d) Mg-O
View Answer
Explanation: Pure covalent bonds form when atoms have same or almost same electronegativity. C-C bond is a bond between two same atoms and Si-O and Al-O have nearly same electronegativity between respective atoms. In Mg-O, the electronegativity of oxygen is more than that of magnesium. Hence it doesn’t have a covalent bond.
2. What happens when two atoms approach each other during covalent bond formation?
a) Electron orbitals overlap
b) Electronic density decreases
c) Bond length increases
d) Electrons are transferred
View Answer
Explanation: When two atoms with similar electronegativity approach each other, the orbitals tend to overlap because of increase in electron density in the nuclei. Thus, electrons are shared and covalent bond is formed.
3. Which of the following is the strongest covalent bond?
a) Pi bond
b) Sigma bond
c) Double bond
d) Triple bond
View Answer
Explanation: Triple bond is the strongest bond. The energy required to cleave the triple is more due to presence of two pi bonds and one sigma bond. Energy required to cleave double bond is lesser due to presence of one sigma and one pi bond. Energy to cleave sigma bond is least but much higher than that needed to cleave a single pi bond.
4. How many covalent bonds are possible in a molecule?
a) 1
b) 2
c) Infinitely many
d) Determined by valence electrons
View Answer
Explanation: Covalent bonds are formed by sharing of electrons. The electrons available for sharing depend on valence electrons present. Sharing of one electron by each atom in a molecule forms one covalent bond. Therefore, number of covalent bonds are determined by valence electrons.
5. Which of the following has weakest covalent bond?
a) Bismuth
b) Diamond
c) Gold
d) Silver
View Answer
Explanation: The melting point of bismuth, gold and silver is 271.4°C, 1064°C and 961.8°C respectively. Diamond is sublime and does not have a melting point. Thermal energy required to cleave covalent bond of bismuth is least. Hence, it has weakest bond.
6. The wider the separation of the constituent atoms of a molecule from lower left to upper right hand corner in the periodic table, more covalent is the bond.
a) True
b) False
View Answer
Explanation: Wider separation between elements in a periodic table means more electronegativity difference between the elements. More electronegativity leads to formation of ionic bond that is, transfer of electrons. Closer the elements in a periodic table, covalent is the bond.
7. What is the shape of p-orbital?
a) Spherical
b) Cylindrical
c) Dumbbell
d) Flat
View Answer
Explanation: The probability of finding the electrons in the bulging side of the dumbbell is more than at the centre of the dumbbell. This is given by Heisenberg Uncertainty Principle. Therefore, it is of dumbbell shaped.
8. Covalent bonding is _______
a) directional
b) unique
c) double bond
d) between carbon atoms only
View Answer
Explanation: The atoms bonded covalently orient themselves in specific directions due to sharing of electrons between only specific pairs of atoms and overlapping of orbitals. That is why the orbitals have definite shapes. Thus, covalent bonding is directional.
Sanfoundry Global Education & Learning Series – Ceramics Engineering.
To practice all areas of Ceramics Engineering, here is complete set of Multiple Choice Questions and Answers.
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