Answer pls. how?

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

Which change to the system wood cause the freely-moving piston to lower?

Which statement correctly describes the phosphate ion, ? it is composed of one phosphorus atom and four oxygen atoms covalently bonded together, and there is a –3 charge distributed over the entire ion. it is composed of one phosphorus atom and four oxygen atoms covalently bonded together, and there is a –3 charge on the phosphorus atom. it is composed of one phosphorus atom and four oxygen atoms ionically bonded together, and there is a –3 charge distributed over the entire ion. it is composed of one phosphorus atom and four oxygen atoms ionically bonded together, and there is a –3 charge on the phosphorus atom.