Question

A simple telescope used to view distant objects has eyepiece and objective lens of focal lengths $f_e$ and $f$, respectively. Then,

Answer 1

$i\to a$.
More the radius of aperture more is the amount of light entering the telescope.
$ii\to c$.
$M=\frac{f_0}{f_e}$
$iii\to c$.
$L=f_0+f_e$
$iv.\to a.,b.,d.$
Depends on dispersion of lens, spherical aberration and radius of aperture.