Choose all the answers that apply. Check the statements that are true.

- A hypothesis must be proven true in order for an experiment to be valid.
- Electrons and protons are examples of cycles.
- A valid experiment must have results that can be repeated.
- Observations are the final stage of an experiment.
- Science is based on fact

Select all that apply

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

can you list the answers so i can answer

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8