The pH value of pure water at room temperature is:

Which vitamin is produced in human skin upon exposure to sunlight?

The process by which plants lose water in the form of vapor is called:

Rusting of iron is an example of which type of reaction?

Sound cannot travel through:

The normal body temperature of a healthy human is approximately:

The hardest natural substance found on Earth is:

The energy released when a substance burns in the presence of oxygen is called:

The chemical formula for common table salt is:

Which of these is not a renewable source of energy?

The study of heredity and variation in living organisms is called: