Which of the following compounds will react with $NaHCO_3$ solution to give sodium salt and carbon dioxide?

$\lim _{x \rightarrow 0} \left( \frac{x \cdot 10^x - x}{1 - \cos x} \right)$ is equal to

The layer of the uterus which becomes much eroded due to placental villi is known as

The vectors $\vec{AB} = 3\hat{i} - 2\hat{j} + 2\hat{k}$ and $\vec{BC} = \hat{i} - 2\hat{k}$ are the adjacent sides of a parallelogram. The angle between its diagonals is

In a circuit,the current lags behind the voltage by a phase difference of $\pi / 2$. The circuit contains which of the following?

When a system is taken from state $i$ to state $f$ along the path $iaf$,$Q = 50 \, cal$ and $W = 20 \, cal$. Along the path $ibf$,if $Q = 36 \, cal$,find the work $W$ for the path $ibf$ in $cal$.