If the sum of the distances of a point from two perpendicular lines in a plane is $1$ unit,then its locus is

At what time between $10\,\text{O'clock}$ and $11\,\text{O'clock}$ are the two hands of a clock symmetric with respect to the vertical line (give the answer to the nearest second)?

The line $AB$ cuts off equal intercepts $2a$ from the axes. From any point $P$ on the line $AB$,perpendiculars $PR$ and $PS$ are drawn to the axes. The locus of the mid-point of $RS$ is

$A$ rod of length $2l$ slides with its ends on two perpendicular lines. The locus of its mid-point is

If the equation of a curve remains unchanged by replacing $x$ with $y$ and $y$ with $x$,then the curve is

$A$ variable line $\frac{x}{a}+\frac{y}{b}=1$ is such that $a+b=4$. The locus of the midpoint of the portion of the line intercepted between the axes is