Board-style MCQs and reasoning questions in the BIEK / Sindh Board pattern. Tap an option to check yourself instantly. Solved reasoning questions are at the bottom.
Multiple-choice questions
Solved reasoning & self-assessment (past papers)
Shape & bond angle of H₂O, NH₃ and CH₄
All three have a central atom with 4 electron pairs (sp³).
CH₄: 4 bond pairs, 0 lone → tetrahedral, 109.5°
NH₃: 3 bond + 1 lone → pyramidal, 107°
H₂O: 2 bond + 2 lone → bent, 104.5° (lone pairs squeeze the angle).
Count σ and π bonds in C₂H₄ (ethene) and C₂H₂ (ethyne)
Ethene CH₂=CH₂: 4 C–H σ + 1 C–C σ + 1 C=C π = 5 σ and 1 π
Ethyne HC≡CH: 2 C–H σ + 1 C–C σ + 2 π = 3 σ and 2 π
Why is CO₂ non-polar but SO₂ polar?
CO₂ is linear (no lone pair on C) → the two C=O dipoles are equal and opposite → cancel → non-polar.
SO₂ is bent (a lone pair on S) → the dipoles do not cancel → polar.
Bond order of O₂ from MOT
O₂ has 10 bonding and 6 antibonding electrons.
Bond order = ½(10 − 6) = 2 (a double bond), with 2 unpaired electrons → paramagnetic.
Hybridisation of C in CH₄, C₂H₄ and C₂H₂
CH₄: 4 σ bonds → sp³
C₂H₄: 3 σ + 1 π per carbon → sp²
C₂H₂: 2 σ + 2 π per carbon → sp