In a calcium atom in the ground state, the electron that possess the least amount of energy are located in the
(1) fourth electron shell
(2) first electron
(3) second electron shell
(4) third electron shell

Why should the scientific method be used to answer a question? a. it provides a way to test an idea without any bias. b. it provides a way to test a hypothesis. c. it provides a way to ensure all hypotheses are proven correct. d. it provides a way to quickly turn a hypothesis into a scientific theory.

Based on its chemical properties, identify the position of each chemical family on the periodic table.

Areaction is first order. if the initial reactant concentration is 0.0200 m, and 25.0 days later the concentration is 6.25 x 10-4 m, then its half-life is: