Justify that the following reactions are redox reactions:
$a$. $CuO_{(s)} + H_{2(g)} \rightarrow Cu_{(s)} + H_2O_{(g)}$
$b$. $Fe_2O_{3(s)} + 3CO_{(g)} \rightarrow 2Fe_{(s)} + 3CO_{2(g)}$
$c$. $4BCl_{3(g)} + 3LiAlH_{4(s)} \rightarrow 2B_2H_{6(g)} + 3LiCl_{(s)} + 3AlCl_{3(s)}$
$d$. $2K_{(s)} + F_{2(g)} \rightarrow 2K^{+}F^{-}_{(s)}$
$e$. $4NH_{3(g)} + 5O_{2(g)} \rightarrow 4NO_{(g)} + 6H_2O_{(g)}$

The slope of the normal to the curve $x = \sqrt{t}$ and $y = t - \frac{1}{\sqrt{t}}$ at $t = 4$ is ...

In the given circuit, the current flowing through it is: (in $ A$)

$A$ ray of light along $x+\sqrt{3}y=\sqrt{3}$ gets reflected upon reaching the $x$-axis. The equation of the reflected ray is:

Assertion $(A)$: Equal moles of different substances contain the same number of constituent particles.
Reason $(R)$: Equal weights of different substances contain the same number of constituent particles.
The correct answer is