Oxides of carbon illustrate which law of chemical combination?

Name three elements which make up more than 90 percent of the human body.

When two substances X and Y are mixed together, a new substance Z is formed with the evolution of heat. Properties of Z are different from those of X and Y. Is Z an element, compound or a mixture?

If water samples are taken from sea, rivers, clouds, lakes or snow, they will be found to contain hydrogen and oxygen in the appropriate ratio of 1 : 8. This illustrates which law of chemical combination?

What is atomicity of an element?

Why atomic masses are the average values?

What is the relation between molecular weight and vapour density?

What is Avogadro's number?

What is the relation between gram molecular weight and volume of a gas?

30.

What is SI unit of mole?