Which of the following is an amphoteric hydroxide?

Two photons of energy $2.5 \ eV$ and $3.5 \ eV$ fall on a metal surface of work function $1.5 \ eV$. The ratio of the maximum velocities of the photoelectrons emitted from the metal surface is

If a line makes angles $\frac{\pi}{3}$ and $\frac{\pi}{4}$ with the $X$-axis and $Y$-axis respectively,then the angle made by the line with the $Z$-axis is

$\int_0^\pi \frac{\theta \sin \theta}{1+\cos ^2 \theta} d \theta$ is equal to

Give signs used for floral formula.

$A$ force of $(2\hat i + 3\hat j + 4\hat k) \; N$ acts on a body for $4 \; s$,producing a displacement of $(3\hat i + 4\hat j + 5\hat k) \; m$. The power used is ....... $W$. (in $.5$)