Thorn of $Bougainvillea$ and tendril of $Cucurbita$ are examples of

The atomic weight of an element is $39$. The number of neutrons in its nucleus is one more than the number of protons. The number of protons,neutrons and electrons respectively in its atom would be

Which of the following can show geometrical isomerism?

$\cos A \cos 2 A \cos 4 A \ldots \cos 2^{n-1} A$ equals

An ideal gas is subjected to a cyclic process involving four thermodynamic states. The amounts of heat $(Q)$ and work $(W)$ involved in each of these states are:
$\begin{aligned} & Q_1=6000 \text{ J}, \quad Q_2=-5500 \text{ J}, \quad Q_3=-3000 \text{ J}, \quad Q_4=3500 \text{ J} \\ & W_1=2500 \text{ J}, \quad W_2=-1000 \text{ J}, \quad W_3=-1200 \text{ J}, \quad W_4=x \text{ J} \end{aligned}$
The ratio of the net work done by the gas to the total heat absorbed by the gas is $\eta$. The values of $x$ and $\eta$ respectively are:

Product $(A)$ is