Is the statement "$A$ particle can have zero speed but non-zero velocity" true or false? Explain.

$A$ car moves from $A$ to $B$ with a speed of $30 \ km/h$ and from $B$ to $A$ with a speed of $20 \ km/h$. What is the average speed of the car (in $km/h$)?

$A$ person walks along a straight road from his house to a market $2.5 \,km$ away with a speed of $5 \,km/h$ and instantly turns back and reaches his house with a speed of $7.5 \,km/h$. The average speed of the person during the time interval $0$ to $50 \,min$ is (in $m/s$)

$A$ car moves a distance of $200 \; m$. It covers the first half of the distance at a speed of $40 \; km/h$ and the second half of the distance at a speed of $v$. If the average speed is $48 \; km/h$,the value of $v$ is: (in $; km/h$)

The ratio of the numerical values of the average velocity and average speed of a body is always

If a body covers one-third of its total distance at speed $v_1$,the next one-third at speed $v_2$,and the last one-third at speed $v_3$,then the average speed will be: