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

As the velocity of particle in uniform circular motion is constant in magnitude but changes direction. So, the acceleration is also constant in magnitude but not in direction.