What is experimental value?? where is it or how do you calculate it??Also what is accepted value?

An atom of lithium-7 has an equal number of(1) electrons and neutrons(2) electrons and protons(3) positrons and neutrons(4) positrons and protons

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.

Select the correct lewis structure for fluorine which is group 7a element?