What is an ore of iron?

The electrical conductivity and melting point of an alloy is:

Which of the following pairs will give displacement reactions?

When a copper wire is left in silver nitrate solution,it is observed that the solution turns bluish green.
$(a)$ Explain the observation.
$(b)$ Write the balanced chemical equation to represent the change taking place.

Which of the following is an alloy?

Account for the following:
$(a)$ Aluminium is more reactive than iron,but its corrosion is less than iron.
$(b)$ Hydrogen gas is not evolved when zinc metal reacts with dilute $HNO_3$.
$(c)$ Carbon is not used for reducing aluminium from aluminium oxide.