What distinguishes an insect from a crustacean?

${ }^{15}P_8 = A + 8 \cdot { }^{14}P_7 \Rightarrow A = $

The proposition $(p$ $\Rightarrow \;\sim p) \wedge (\sim p$ $\Rightarrow p)$ is a

Calcium hydride on hydrolysis forms

The figure shows a rough sketch of a meter bridge. The galvanometer $(G)$ shows zero deflection at a length $\ell \, cm$. Now,$R_1$ and $R_2$ are interchanged,then the balancing length increases by $25 \, cm$. Find the ratio $R_1/R_2$.

Consider two statements $S_1$ and $S_2$.
$S_1$: If $f(x)$ is a differentiable function with $f'(x) = 0$ in $(a, b)$ and $f(x)$ is increasing in $(a, b)$,then $\frac{f(x)}{f'(x)}$ is also increasing in $(a, b)$.
$S_2$: Both $\sin x$ and $\tan x$ are increasing functions in $(0, \frac{\pi}{2})$.
Which of the following is true?