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. 

DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the basis for biological inheritance. Complementary base pairing helps prevent errors in DNA replication.

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.

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."

Jupiter has 67 natural satellites. Eight of Jupiter's moons are regular satellites, with 4 large, spherical moons, and 4 smaller moons that orbit closer to Jupiter. Jupiter has an additional 55 tiny irregular satellites.

The planet with the second highest number of moons is Saturn, with 61 moons.

Earth has only one natural satellite i.e, Moon.

Mercury and Venus have no satellites.