Four elements W, X, Y and Z have atomic numbers 2, 6, 16 and 20 respectively. Which of these elements is a metal?

When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as

A catalyst increases the rate of a chemical reaction by providing a path that

The removal of rust from iron by treatment with tetraoxosuplhate(VI)acid is based on the