Which of the following is the most effective in causing the coagulation of a ferric hydroxide sol?

If $z = \sec^{-1}\left(\frac{x^4+y^4-8x^2y^2}{x^2+y^2}\right)$,then $x \frac{\partial z}{\partial x} + y \frac{\partial z}{\partial y}$ is equal to

In an experiment with a beam balance,an unknown mass $m$ is balanced by two known masses of $16\,kg$ and $4\,kg$ as shown in the figure. The value of the unknown mass $m$ is ......... $kg$.

Consider the reaction at $300\, K$:
$C_6H_{6(l)} + \frac{15}{2} O_{2(g)} \to 6 CO_{2(g)} + 3 H_2O_{(l)}$; $\Delta H = -3271\, kJ$
What is $\Delta U$ for the combustion of $1.5\, mol$ of benzene at $27\, ^\circ C$? .....$kJ$

Emulsification of $10 \, mL$ of oil in water produces $24 \times 10^{18}$ droplets. If the surface tension at the oil-water interface is $0.03 \, J \, m^{-2}$ and the area of each droplet is $12.5 \times 10^{-16} \, m^2$,the energy spent in the formation of oil droplets is $.... \, J$.

$A$ mass $m$ moves with a velocity $v$ and collides inelastically with another identical mass initially at rest. After collision,the first mass moves with velocity $\frac{v}{\sqrt{3}}$ in a direction perpendicular to its initial direction of motion. The speed of the second mass after collision is: