In a Ruby laser, the colour of laser light is due to ______ atom.

Consider the following gaseous equilibrium in a closed container of volume $V$ at $T \text{ K}$:
$P_{2(g)} + Q_{2(g)} \rightleftharpoons 2PQ_{(g)}$.
$2 \text{ moles}$ each of $P_{2(g)}$, $Q_{2(g)}$, and $PQ_{(g)}$ are present at equilibrium. Now, $1 \text{ mole}$ each of $P_{2}$ and $Q_{2}$ are added to the equilibrium while keeping the temperature at $T \text{ K}$. The number of moles of $P_{2}$, $Q_{2}$, and $PQ$ at the new equilibrium, respectively, are:

$\int \frac{1+x+\sqrt{x+x^2}}{\sqrt{x}+\sqrt{1+x}} d x$ is equal to

When $MnO_2$ is fused with $KOH$ in the presence of air,a coloured compound is formed. Identify the product and its colour.

An electron of mass $m$ when accelerated through a potential difference $V$ has de-Broglie wavelength $\lambda$. The de-Broglie wavelength associated with a proton of mass $M$ accelerated through the same potential difference will be:

Which of the following facilitates the opening of the stomatal aperture?