$L t_{θ → 0} \frac{θ}{\sin{θ}} = ?$

Evaluate the following limits.

$\displaystyle\lim_{x\rightarrow 0}\dfrac{\sqrt{2-x}-\sqrt{2+x}}{x}$.

If the function $f(x) = (1 - x)\tan \dfrac{{\pi x}}{2}$ is continuous at $x = 1$ ,then $f(1)=$

$\displaystyle \lim _{x \rightarrow 0} \dfrac{x \tan 2 x-2 x \tan x}{(1-\cos 2 x)^{2}}$ is equal to

$\lim_{x → 0} 2^{x} \sin \frac{b}{2^{x}} = ?$