Which concentrations can be calculated if the mole fraction and density of an aqueous solution of $HCl$ are known?
$1.$ Molality $\ \ 2.$ Molarity $\ \ 3.$ $\%(w/w)$

If the lines $4x + 3y - 1 = 0$,$x - y + 5 = 0$ and $kx + 5y - 3 = 0$ are concurrent,then $k$ is equal to:

In the figure shown,the velocities of different blocks are given. The velocity of $C$ is $.........\,m/s$.

$A$ wire,which passes through the hole in a small bead,is bent in the form of a quarter of a circle. The wire is fixed vertically on the ground as shown in the figure. The bead is released from near the top of the wire and it slides along the wire without friction. As the bead moves from $A$ to $B$,the force it applies on the wire is

$A$ wheel has an angular acceleration of $3.0\, rad/s^2$ and an initial angular speed of $2.00\, rad/s$. In a time of $2\, s$,it has rotated through an angle (in radians) of:

Which one of the following correctly represents the variation of electronegativity $(EN)$ with atomic number $(Z)$ of group $13$ elements?