Question

Define power of lens and state it's S.I unit.​

Answer 1

Answer:

Power of lens is known as the inverse of the focal length of the lens measured in meter(m). S.I unit of power = Dioptre (D) Power of lense = 1/ focal length in meter. The focal length of 1st lense f1 = 40 cm = 0.4 m. The lense used is a convex lens because the focal length is a positive value.

Answer 2

Explanation:

General Methods of Preparation of Haloalkanes

1. From Alcohols

In Groove’s method, ZnC12 is used to weaken the C-OH bond. In case of 3° alcohols, ZnC12 is not required.

The reactivity order of halogen acids is HI > HBr > HCl.

Darzen procedure is the best method for preparing alkyl halides from alcohols since both the by products (SO2 and HCl) are gaseous and escape easily.