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81.

If a engine working on Otto cycle has its compression ratio raised from 5 to 6 the percentage increase in air standard efficiency will be

82.

During adiabatic compression

A.	No heat leaves or enters the system	B.	Maximum work is done
C.	Specific heat remains constant	D.	Temperature remains constant
E.	None of the above

83.

In isothermal compression

A.	There is no gain internal energy	B.	Temperature increses very slowly
C.	There is no exchange of heat with environment	D.	Entropy changes is zero
E.	None of the above

84.

The work done in compressing 1 kg of air in compression will be least when the value of index is

85.

Stoichiometric ratio is

A.	Chemically correct air-fuel ratio by volume	B.	Chemically correct air-fuel ratio by weight
C.	Theoretical mixture of air for complete combustion	D.	Actual ratio of air to fuel for maximum efficiency
E.	None of the above

86.

An air fuel ratio 8 will have

87.

A rich mixture will have an air-fuel ratio

A.	Less than chemically correct	B.	More than chemically correct
C.	Chemically correct	D.	Any of the above
E.	None of the above

88.

During idling a petrol engine requires

89.

Hot spots are

A.	Defects in S.I.engines	B.	The hottest spots in engines
C.	The spots where heavier fractions of fuel are vaporised	D.	Do not exist in engines
E.	Hottest point within engine cylinder

90.

Thermal efficiency of C.I. engines on weak mixtures is