$\cos \alpha \sin (\beta-\gamma)+\cos \beta \sin (\gamma-\alpha)+\cos \gamma \sin (\alpha-\beta)$ is equal to

$A$ sinusoidal voltage of peak value $200 \ V$ is connected to a diode and a resistor $R$ in the circuit shown,such that half-wave rectification occurs. If the forward resistance of the diode is negligible compared to $R$,the rms voltage (in volt) across $R$ is approximately:

Based on the following thermochemical equations:
$H_2O_{(g)} + C_{(s)} \to CO_{(g)} + H_{2(g)}; \Delta H = 131 \ kJ$
$CO_{(g)} + \frac{1}{2}O_{2(g)} \to CO_{2(g)}; \Delta H = -282 \ kJ$
$H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(g)}; \Delta H = -242 \ kJ$
$C_{(s)} + O_{2(g)} \to CO_{2(g)}; \Delta H = X \ kJ$
The value of $X$ will be $...... \ kJ$.

If a source of power $4 \, kW$ produces $10^{20}$ photons/second, the radiation belongs to a part of the spectrum called

What does the part labeled '$A$' in the given figure represent?

Product $(A)$ is