Which of the following corrosion types is difficult to monitor and extremely dangerous?

Consider the following statements:

1. Tarnishing of silver.
2. Rusting of iron.
3. Development of a green coating on copper and bronze.

Which of the statement(s) given above is/are correct with respect to corrosion?

The addition of molybdenum is particularly made steels _____.

Which of the following steel galvanising techniques is used?

A. Hot-dip galvanising
B. Cold galvanising
C. Thermal mists
D. Electroplating

Which of the following means using a metal that does not corrode to cover a more corrosive metal?

When a copper vessel is exposed to moist air for long, it acquires a dull green coating. The green coating is due to:

1. formation of $\left[Cu{\left(OH\right)}_2\right]$
2. formation of $CuC{O}_3$
3. formation of $CuHC{O}_3$
4. Both (1) and (2)

Codes:
A  B C  D