Questions

The International Waste Picker's Day is observed on 1st March in memory of the massacre in Colombia in which 11 workers were brutally killed University of Barranquilla.

Passivity of iron is due to formation of an extremely thin and impervious film of ferrosoferric oxide Fe3O4on the surface of iron. Chromic acid, being a powerful oxidising agent (like nitric acid ) renders iron passive. 

1. Eminent space scientist and former Indian Space Research Organisation (ISRO) Chairman Udupi Ramachandra Rao passed away due to age related ailments. He was 85.

2. He was currently serving as the chairman of the governing council of the Physical Research Laboratory in Ahmedabad. Rao served as the chairman of ISRO for 10 years from 1984-1994.

It is MISSISSIPPI.

90 D in RA means 90 Degrees in Right Angle. It is a logic question which is to be eloborated.

Some more of its kind are:

1. 52 W in a Y     -    52 Weeks in a Year

2. 7 C in a R        -    7 Colours in a Rainbow

3. 9 P in SS

4. 5 C in an OF

5. 12 S of the Z