Questions

Mahadev Govind Ranade is known as the father of Indian Economics. M G Ranade advocated social reforms such as widow re-marriage, liberation of women & emancipation of the oppressed classes.

He was Known to be the mentor & political guru of Gopal Krishna Gokhale & Bal Gangadhar Tilak.

Qualm means feeling confused, uneasiness, very doubtful and being in worry.

Hence, among the given options, Qualm is the opposite of Confidence.

Charles Macintosh (29 December 1766 – 25 July 1843) was a Scottish chemist and inventor of waterproof fabrics.He devoted all his spare time to science, particularly chemistry, and before he was twenty resigned his clerkship to take up the manufacture of chemicals. In this he was highly successful, inventing various new processes. His experiments with one of the by-products of tar, naphtha, led to his invention of waterproof fabrics.

PFD's : Personal Flotation Devices (life jackets).

It is a legal requirement for a PFD to

1. Must be in good, serviceable condition 

2. PFDs must be properly sized for the intended wearer.

3. Sizing for PFDs is based on body weight and chest size.

Diamond is the hardest substance available on Earth.

Diamond is the hardest substance available on Earth due to the giant molecular structure of diamond in which each carbon atom is covalently bonded to four other carbon atoms. A covalent bond is very strong and requires a large amount of energy to break itself, and diamond has many covalent bonds.