starts at 40 Degree after bottom dead centre and ends at 30 Degree before top dead centre

starts at 40 Degree before bottom dead centre and ends at 30 Degree after bottom dead centre

starts at bottom dead centre and ends at top dead centre

may start and end anywhere

Right

Wrong

lean

rich

chemically correct

none of these

U₂₃₄ = 0.006%, U₂₃₅ = 0.712% and U₂₃₈ = 99.282%

U₂₃₄ = 0.712%, U₂₃₅ = 0.006% and U₂₃₈ = 99.282%

U₂₃₄ = 99.282%, U₂₃₅ = 0.006% and U₂₃₈ = 0.712%

U₂₃₄ = 0.006%, U₂₃₅ = 99.282% and U₂₃₈ = 0.712%

chemically correct air-fuel ratio by weight

chemically correct air-fuel ratio by volume

actual air-fuel ratio for maximum efficiency

none of these