Chemical Bonding — Set 3
Chemistry · रासायनिक बंधन · Questions 21–30 of 40
Cations are formed when an atom?
Correct Answer: C. Loses electrons
• **Electron loss** = When an atom releases one or more valence electrons, it has more protons than electrons, creating a positive charge. • **Metals readily ionize** — Groups 1-2 metals lose electrons easily due to low ionization energies and empty d orbitals. • 💡 Wrong-option analysis: A: Sharing electrons creates covalent bonds; B: Protons cannot be gained or lost in normal chemistry; D: Gaining electrons creates anions, not cations.
What is the shape of a Boron Trifluoride (BF3) molecule?
Correct Answer: A. Trigonal planar
• **Trigonal planar geometry** = Boron forms three B-F bonds and has no lone pairs, arranging the fluorines at **120 degrees** around boron. • **sp2 hybridization** — The three hybrid orbitals are oriented in a flat plane to minimize electron pair repulsion. • 💡 Wrong-option analysis: B: Linear requires only two bonds; C: Tetrahedral requires four bonds or lone pairs; D: Pyramidal requires lone pair repulsion.
Anions are formed by which type of elements generally?
Correct Answer: A. Non-metals
• **Non-metal preference** = Non-metals have high electronegativity and electron affinity, pulling electrons from other atoms strongly. • **Complete octets** — Halogens and chalcogens gain electrons to achieve stable noble gas configurations. • 💡 Wrong-option analysis: B: Metals lose electrons to form cations; C: Noble gases have full valence shells and rarely form ions; D: Metalloids rarely participate in ionic bonding.
Which of the following has a coordinate bond?
Correct Answer: B. NH4+
• **Ammonium bonding** = The NH4+ ion forms when ammonia's lone pair on nitrogen bonds to an empty orbital on H+. • **One coordinate bond** — The fourth N-H bond in NH4+ is dative, while the other three are regular covalent bonds. • 💡 Wrong-option analysis: A: Water has two covalent bonds; C: Sodium chloride has ionic bonding; D: Hydrogen chloride has a regular covalent bond.
What is the primary reason atoms form chemical bonds?
Correct Answer: B. To achieve stability
• **To achieve stability** = Atoms bond to achieve a lower potential energy and a more stable electron configuration. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: To gain radioactivity; C: To increase mass; D: To increase volume
Which bond is responsible for the formation of crystals in Sodium Chloride?
Correct Answer: A. Electrostatic force
• **Electrostatic force** = Electrostatic forces of attraction between oppositely charged ions form the ionic lattice. • (Contextual detail from explanation) • 💡 Wrong-option analysis: B: Covalent bond; C: Hydrogen bond; D: Van der Waals force
Which of these is the weakest bond/force?
Correct Answer: C. Van der Waals force
• **Van der Waals force** = Van der Waals forces are the weakest type of intermolecular attraction. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Covalent bond; B: Ionic bond; D: Hydrogen bond
What is the bond angle in a linear molecule like BeCl2?
Correct Answer: B. 180 degrees
• **180 degrees** = The bond angle in a linear molecule is 180 degrees. • **180** — The bond angle in a linear molecule is 180 degrees • 💡 Wrong-option analysis: A: 90 degrees; C: 120 degrees; D: 104.5 degrees
Which type of hybridization is found in Ethylene (C2H4)?
Correct Answer: B. sp2
• **sp2** = The carbon atoms in ethylene are sp2 hybridized to form the double bond. • **120** — This leads to a planar structure with bond angles of approximately 120 degrees • 💡 Wrong-option analysis: A: sp3; C: sp; D: dsp2
Which rule states that orbitals are filled with one electron each before pairing starts?
Correct Answer: B. Hund's Rule
• **Hund's Rule** = Hund's Rule states that electrons occupy degenerate orbitals singly before pairing occurs. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Pauli Exclusion Principle; C: Octet Rule; D: Aufbau Principle