$H_3BO_3$ is

If the system of equations $x + 2y - 3z = 1$,$(k + 3)z = 3$,and $(2k + 1)x + z = 0$ is inconsistent,then the value of $k$ is:

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:

If,in a $\triangle ABC$,$\tan \frac{A}{2} = \frac{5}{6}$ and $\tan \frac{C}{2} = \frac{2}{5}$,then $a, b, c$ are such that :

$A$ uniform chain of length $L$ is lying on a horizontal table. If the coefficient of friction between the chain and the table top is $\mu$,what is the maximum length of the chain that can hang over the edge of the table without disturbing the rest of the chain on the table?

Which one of the following items gives its correct total number?