What does it mean if elements are in the same group on the periodic table?

The atomic number, or number, is the described as the number of in the nucleus of an chemical element.

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?

Energy defines the different "states" of matter. in no more than 3 sentences, describe the amount of kinetic energy that each of the 3 states of matter possesses and relate that to the atom/molecular motion of each "state".