Which is the best material for studying mitosis in a laboratory?

Which of the following substances is the most acidic?

If $\tan (\pi \cos \theta)=\cot (\pi \sin \theta)$,then a value of $\cos \left(\theta-\frac{\pi}{4}\right)$ among the following is

$A$ solid reflects incident light and its electrical conductivity decreases with temperature. The binding in this solid is:

$A$ wheel having a moment of inertia $2 \, kg \cdot m^{2}$ about its vertical axis rotates at the rate of $60 \, rpm$ about this axis. The torque which can stop the wheel's rotation in one minute would be:

Energy is being emitted from the surface of a black body at $127^{\circ}C$ temperature at the rate of $1.0 \times 10^6 \ J/\text{s} \cdot \text{m}^2$. The temperature of the black body at which the rate of energy emission is $16.0 \times 10^6 \ J/\text{s} \cdot \text{m}^2$ will be ......... $^{\circ}C$.