The focal length of the mirror is the distance between the pole of the mirror & the screen where the clear image of the distant object is formed. As the mirror stand is at 10cm & screen is at 40 ...

The power of combination of two lenses is P = P₁ + P₂, Where P₁ is the power of the convex lens of focal length 20 cm & P₂ is power of concave lens of focal length of 25 cm.

Because it is covalent compound formed by sharing of electrons. Whereas, in other three compounds are ionic compounds & they conduct electricity in their molten state.

Sublimation method of purification is used for those solids which are directly converted to gas phase without undergoing liquid phase. So, R is separated from rest of the solids by sublimation.

(i) Striated muscles (ii) Smooth muscles (iii) Cardiac muscles (iv) Skeletal muscles