Chemical Bonding — Set 3
Chemistry · रासायनिक बंधन · Questions 21–30 of 40
Cations are formed when an atom?
Correct Answer: C. Loses electrons
A cation is a positively charged ion formed when a neutral atom loses one or more electrons. Metals typically form cations because they have low ionization energies. Sodium (Na+) is a common cation found in table salt.
What is the shape of a Boron Trifluoride (BF3) molecule?
Correct Answer: A. Trigonal planar
Boron Trifluoride has a trigonal planar shape with bond angles of 120 degrees. The boron atom is surrounded by three bonding pairs and no lone pairs. Boron is an exception to the octet rule as it is stable with six electrons.
Anions are formed by which type of elements generally?
Correct Answer: A. Non-metals
Anions are negatively charged ions formed when atoms gain electrons. Non-metals generally form anions because they have high electronegativities and electron affinities. The chloride ion (Cl-) is a well-known example of an anion.
Which of the following has a coordinate bond?
Correct Answer: B. NH4+
The ammonium ion (NH4+) contains one coordinate covalent bond. It is formed when an ammonia molecule (NH3) shares its lone pair with a hydrogen ion (H+). Once formed, the coordinate bond is indistinguishable from other covalent bonds.
What is the primary reason atoms form chemical bonds?
Correct Answer: B. To achieve stability
Atoms bond to achieve a lower potential energy and a more stable electron configuration. This usually involves reaching a full valence shell similar to noble gases. Stability is the driving force behind most chemical reactions.
Which bond is responsible for the formation of crystals in Sodium Chloride?
Correct Answer: A. Electrostatic force
Electrostatic forces of attraction between oppositely charged ions form the ionic lattice. In NaCl, Na+ and Cl- ions are held together in a repeating 3D cubic structure. This strong attraction results in a very high melting point.
Which of these is the weakest bond/force?
Correct Answer: C. Van der Waals force
Van der Waals forces are the weakest type of intermolecular attraction. They include dispersion forces and dipole-dipole interactions. These forces play a significant role in the properties of organic compounds and gases.
What is the bond angle in a linear molecule like BeCl2?
Correct Answer: B. 180 degrees
The bond angle in a linear molecule is 180 degrees. This occurs when two bonding pairs of electrons are positioned as far apart as possible. Carbon dioxide is another common example of a linear molecule.
Which type of hybridization is found in Ethylene (C2H4)?
Correct Answer: B. sp2
The carbon atoms in ethylene are sp2 hybridized to form the double bond. This leads to a planar structure with bond angles of approximately 120 degrees. Ethylene is a key starting material in the plastic industry.
Which rule states that orbitals are filled with one electron each before pairing starts?
Correct Answer: B. Hund's Rule
Hund's Rule states that electrons occupy degenerate orbitals singly before pairing occurs. This minimizes electron-electron repulsion within the subshell. It helps in determining the magnetic properties of different elements.