The ___________ of a radioactive isotope is the time required for half of the nuclei in a sample to decompose.

How many neutrons are in the nucleus of Copper? (Copper (Cu): mass number is 64 and atomic number is 29).

Elements in the same group in the periodic table:

An element is a pure substance that cannot be broken down into anything simpler by physical or chemical means.

Drinking water regulations are the responsibility of the

The substance used to kill bacteria in raw water is called:

Identify A  [BLANK-1]

Developed law implying “atomic numbers are more important than atomic weights”

In nuclear __________, the nuclei of light isotopes combine to produce heavy elements.

He showed relation between electricity and chemical activity.