Solution:
A, B, C are wrong because Assertion is not correct.
Actually , if magnitude of vector is zero then it called null vector.
Assertion (A) : A physical quantity cannot be called as a vector if its magnitude is zero Reason (R) : A vector has both magnitude and direction
Assertion (A) : A physical quantity cannot be called as a vector if its magnitude is zero
Reason (R) : A vector has both magnitude and direction
