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 $|a|=1, |b|=2$ and the angle between $a$ and $b$ is $120^{\circ}$,then ${(a+3b) \times (3a-b)}^2$ is equal to

The length of an elastic string is $a$ metres when the longitudinal tension is $4 \ N$ and $b$ metres when the longitudinal tension is $5 \ N$. The length of the string in metres when the longitudinal tension is $9 \ N$ is

The correct order of increasing $s-$character (in percentage) in the hybrid orbitals of the following molecules/ions is:
$(I)$ $CO_3^{2-}$ $(II)$ $XeF_4$ $(III)$ $I_3^-$ $(IV)$ $NCl_3$ $(V)$ $BeCl_2$

The rate of disintegration of a fixed quantity of a radioactive element can be increased by

An $X$-ray tube produces a continuous spectrum of radiation with its shortest wavelength of $45 \times 10^{-2} \text{ \AA}$. The maximum energy of a photon in the radiation in $eV$ is $(h = 6.62 \times 10^{-34} \text{ J-s}, c = 3 \times 10^8 \text{ m/s})$. (in $27,500$)