What is the tube length of a compound microscope?

$A$ microscope consists of an objective of focal length $1.9 \,cm$ and an eyepiece of focal length $5 \,cm$. The two lenses are kept at a distance of $10.5 \,cm$. If the image is to be formed at the least distance of distinct vision, the distance at which the object is to be placed before the objective is (least distance of distinct vision is $25 \,cm$). (in $\,cm$)

In a compound microscope,the focal lengths of two lenses are $1.5 \text{ cm}$ and $6.25 \text{ cm}$. An object is placed at $2 \text{ cm}$ from the objective and the final image is formed at $25 \text{ cm}$ from the eye lens. The distance between the two lenses is .............. (in $\text{cm}$).

$A$ thin convex lens of focal length $5 \, cm$ is used as a simple microscope by a person with a normal near point located $25 \, cm$ away. What is the magnifying power of the microscope?

We wish to make a microscope with the help of two positive lenses,both with a focal length of $20\, mm$ each,and the object is positioned $25\, mm$ from the objective lens. How far apart should the lenses be so that the final image is formed at infinity?......$mm$

$A$ compound microscope has two lenses. The magnifying power of one is $5$ and the combined magnifying power is $100$. The magnifying power of the other lens is