Engine

For a spark ignition engine, the equivalence ratio ()φof mixture entering the
combustion chamber has values:

(A) 1 < φ for idling and 1 > φ for peak power conditions
(B) 1 > φ for both idling and peak power conditions
(C) 1 > φ for idling and 1 < φ for peak power conditions
(D) 1 < φ for both idling and peak power conditions.

 A diesel engine is usually more efficient than a spark ignition engine because:

(A) diesel being a heavier hydrocarbon, releases more heat per kg than
gasoline
(B) the air standard efficiency of diesel cycle is higher than the Otto cycle,
at a fixed compression ratio
(C) the compression ratio of a diesel engine is higher than that of an SI
engine
(D) self ignition temperature of diesel is higher than that of gasoline