Questions

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. 

There are 60 minutes in an hour.

In ¾ of an hour there are (60 × ¾) minutes = 45 minutes.

In ¾ of an hour there are (60 × 45) seconds = 2700 seconds.

Siren sounds for every 5 seconds.

In 2700 seconds = 2700/5 = 540 times.

The count start after the first sound, the Siren will sound 541 times in ¾ of an hour.

Beautiful means good looking, having pleasing personality, glamourous, charming.

Synonyms of Beautiful are handsome, attractive, alluring, cute, fair,...

Hence, in the given options Synonym of 'Beautiful' is Alluring.

State-run NTPC said the company has forayed into electric vehicle charging business and has set up first such charging stations at its offices in Delhi and Noida. Adding that the move will push demand for electric vehicles, an official said, "The main objective in setting up the charging points is to be part of promoting clean energy transportation."