Automobile Engineering in ME
The compression ratio in petrol engine is kept less than in Diesel engine because

It makes petrol engines lighter
It is just customary to have less compression ratio in petrol engines
Less compression ratio gives better performance
Higher or equivalent compression ratio in petrol engines is not possible due to pre-ignition

ANSWER DOWNLOAD EXAMIANS APP

Automobile Engineering in ME
An imbalance wheel during vehicle operation

Makes large noise when its heavy point hits the road surface
Deflects in the vehicle's longitudinal direction
Creates a standing wave
Bounces vertically or deflects from side to side (as seen from front or rear)

ANSWER DOWNLOAD EXAMIANS APP