The number of atoms in $100 \text{ g}$ of an $fcc$ crystal with density $d = 10 \text{ g/cm}^3$ and cell edge equal to $100 \text{ pm}$ is equal to:

Let $a, b \in R$. If the mirror image of the point $P(a, 6, 9)$ with respect to the line $\frac{x-3}{7} = \frac{y-2}{5} = \frac{z-1}{-9}$ is $(20, b, -a-9)$,then $|a+b|$ is equal to:

Which of the following pairs of ions have the same paramagnetic moment?

The work function of a metal is $2 \text{ eV}$. If a radiation of wavelength $3000 \text{ Å}$ is incident on it,the maximum kinetic energy of the emitted photoelectrons is (Planck's constant $h = 6.6 \times 10^{-34} \text{ J s}$; velocity of light $c = 3 \times 10^8 \text{ m/s}$; $1 \text{ eV} = 1.6 \times 10^{-19} \text{ J}$)

If $\frac{1}{x(x^2 + 1)} = \frac{A}{x} + \frac{Bx + C}{x^2 + 1}$,then $(A, B, C) = $

Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile,$E^{+}$:
$(a)$ Chlorobenzene,$2,4-$dinitrochlorobenzene,$p-$nitrochlorobenzene
$(b)$ Toluene,$p-CH_3-C_6H_4-NO_2$,$p-O_2N-C_6H_4-NO_2$