2. when atoms are heated so that they emit light, what characteristic of their light

allows you to tell one atom from another?

The color of the light.

Explanation:

When an atom is heated, its electrons are excited and they jump to higher energy levels. The electrons will return to their normal energy level, and by doing this, they will emit a photon of energy, which is in the form of light. The color of the light depends on the difference of energy of the two levels, and because of that is different for each element.

what is the volume occupied by 40 grams of argon gas (ar) at standard conditions? what volume, in liters, is occupied by 1.5 x 1023 

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.