Automobile Engineering in ME
The condition that causes vapour locking in a brake system is

Keeping the vehicle without use for an extended period
Overheating of the fluid due to frequent brake application
An excessively high engine speed on a downhill road
Overcooling of the brakes during high speed driving

ANSWER DOWNLOAD EXAMIANS APP

Automobile Engineering in ME
In a ventilated disc brake

Caliper is covered with cooling fins
A duct directs air towards the caliper for cooling while the vehicle is moving
Disc contains radial vanes between its rubbing surfaces for optimum cooling performance
Disc contains many small holes for optimum cooling performance

ANSWER DOWNLOAD EXAMIANS APP