The locus of the midpoints of the chords of the parabola $y^2 = 4ax$ which pass through the origin is:

$A$ gas at the temperature $250\, K$ is contained in a closed vessel. If the gas is heated through $1\, K$, then the percentage increase in its pressure will be .... $\%$

How many even numbers of $3$ different digits can be formed from the digits $1, 2, 3, 4, 5, 6, 7, 8, 9$ (repetition is not allowed)?

$A$ bar of cross-sectional area $A$ is subjected to two equal and opposite tensile forces at its ends as shown in the figure. Consider a plane $BB'$ making an angle $\theta$ with the length. The ratio of tensile stress to the shearing stress on the plane $BB'$ is

If $A$ and $B$ are two sets,then $A \cap (A \cup B)'$ is equal to

$A$ microscope consists of an objective of focal length $1.9 \ cm$ and an eyepiece of focal length $5 \ cm$. The two lenses are kept at a distance of $10.5 \ cm$. If the image is to be formed at the least distance of distinct vision $(25 \ cm)$,the distance at which the object is to be placed before the objective is: (in $cm$)