Question

A particle moves on a straight line with a uniform velocity. Its angular momentum
(a) is always zero
(b) is zero about a point on the straight line
(c) is not zero about a point away from the straight line
(d) about any given point remains constant.

Answer 1

(b) is zero about a point on the straight line
(c) is not zero about a point away from the straight line
(d) about any given point remains constant.

Explanation: 

The angular momentum of a particle about a point =mvr {Where r is the perpendicular distance of the line of velocity from the point} Since for a point on the line, r = 0, and for a point away from the line, r is not zero. 

Hence (b) and (c). And for a given point r = constant, hence (d).