line and continuous spectrum

No, the above answers are really NOT correct.

Pressure exhibited by a gas is due to the change of momentum of gas molecules when they bombard a surface. It is entirely unelated to the energy level of orbital electrons.

Transistion of orbital electrons from a higher orbit (energy level) to a lower orbit (lower energy level) emits electromagnetic waves. If the wavelength of the wave emitted is within the visible spectrum, then spectral lines are observed. A collection of these spectral lines constitutes a 'line spectrum'.

On the other hand, atoms in solids are closely packed, electron orbits of the atoms are overlapping with one another, thus forming a continuous energy level (i.e. a band of energy). Transistion of electrons can happen at any level with the energy band, thus producing a continuous spectrum.

錯解了。多謝樓下指正。