Chemical Bonding — Set 2
Chemistry · रासायनिक बंधन · Questions 11–20 of 40
Which factor primarily determines the polarity of a covalent bond?
Correct Answer: D. Electronegativity difference
The difference in electronegativity between two atoms determines if a bond is polar or non-polar. If the difference is significant, the electrons are pulled closer to the more electronegative atom. This creates partial positive and negative charges at the ends of the bond.
Which theory explains the shape of molecules based on the repulsion of valence electron pairs?
Correct Answer: C. VSEPR Theory
VSEPR theory stands for Valence Shell Electron Pair Repulsion theory. It assumes that electron pairs around a central atom will stay as far apart as possible. This theory helps in predicting the 3D structures of simple molecules.
Which of the following properties is characteristic of most ionic compounds?
Correct Answer: A. High electrical conductivity in molten state
Ionic compounds conduct electricity when melted or dissolved in water because ions become free to move. In the solid state, they are insulators because ions are locked in a lattice. They generally have very high melting and boiling points.
The 'Sea of Electrons' model is used to describe which type of bonding?
Correct Answer: D. Metallic
Metallic bonding involves a lattice of positive metal ions surrounded by a sea of delocalized electrons. These mobile electrons are responsible for the high electrical and thermal conductivity of metals. This model also explains why metals are malleable and ductile.
Which molecule has a trigonal pyramidal shape?
Correct Answer: D. NH3
Ammonia (NH3) has a trigonal pyramidal shape because of one lone pair on the nitrogen atom. The lone pair takes up more space than bonding pairs, pushing the hydrogens down. The bond angle in ammonia is approximately 107 degrees.
Which bond is the strongest among the following?
Correct Answer: B. Triple bond
A triple bond is the strongest because it involves the sharing of six electrons between two atoms. More shared electrons lead to a shorter bond length and higher bond energy. Breaking a triple bond requires significantly more energy than a single or double bond.
Which of the following is a non-polar molecule despite having polar bonds?
Correct Answer: A. Carbon dioxide
Carbon dioxide is non-polar because its linear geometry allows the polar bonds to cancel each other out. The individual C=O bonds are polar, but the overall dipole moment of the molecule is zero. Symmetry plays a crucial role in determining the net polarity of a molecule.
Hybridisation involves the mixing of which of the following?
Correct Answer: B. Atomic orbitals
Hybridisation is the concept of mixing atomic orbitals to form new hybrid orbitals suitable for bonding. These new orbitals have different energies and shapes than the original atomic orbitals. This process helps explain the observed bond angles in molecules like methane.
Which element has the highest electronegativity in the periodic table?
Correct Answer: A. Fluorine
Fluorine is the most electronegative element with a value of 4.0 on the Pauling scale. It has the strongest tendency to attract shared electrons in a chemical bond. This makes it highly reactive and capable of forming very polar bonds.
Which type of bond is found in a molecule of Oxygen (O2)?
Correct Answer: C. Double covalent bond
Oxygen molecules consist of two oxygen atoms joined by a double covalent bond. Each oxygen atom shares two of its valence electrons to complete its octet. Oxygen is essential for respiration in most living organisms.