A) Both A and R are true and R is the correct explanation of the assertion. b) Both A and R are true, but R is not the correct explanation of the assertion.
c) A is true, but R is false.
d) A is false, but R is true.
4. Assertion: Distance-time graph of a stationary object is a straight line parallel to the time
axis.
Reason: For a stationary object, position does not change with time. (1)
5. Assertion: A bus moving at a constant speed towards north, takes a turn towards east and
continues its motion with the same speed. There will be no change in the velocity of the bus.
Reason: Velocity is a vector quantity. (1)
6. Assertion: Gases have high rate of diffusion. (1)
Reason: Gases have large intermolecular space and weak force of attraction.