In which of the following is the final image erect?

In a microscope of tube length $10 \ cm$, two convex lenses are arranged with focal lengths of $2 \ cm$ and $5 \ cm$. The total magnification obtained with this system for normal adjustment is $(5)^{k}$. The value of $k$ is . . . . . . .

If in a compound microscope $m_1$ and $m_2$ are the linear magnifications of the objective lens and the eye lens respectively,then the magnifying power of the compound microscope will be:

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: For a simple microscope,the angular size of the object equals the angular size of the image.
Reason $R$: Magnification is achieved as the small object can be kept much closer to the eye than $25\, cm$ and hence it subtends a large angle.
In the light of the above statements,choose the most appropriate answer from the options given below:

The focal lengths of the objective and the eye-piece of a compound microscope are $2.0 \, cm$ and $3.0 \, cm$ respectively. The distance between the objective and the eye-piece is $15.0 \, cm$. The final image formed by the eye-piece is at infinity. The two lenses are thin. The distances in $cm$ of the object and the image produced by the objective measured from the objective lens are respectively:

$A$ simple microscope is used to see an object first in blue light and then in red light. Due to the change from blue to red light, what is the effect on its magnifying power?