Question

which of these is more likely to produce an emission spectrum over a continuous spectrum?

1. a planet

2. a cold gas containing only one type of atom

3. a solid material

4. a material with very closely-spaced energy levels

5. a heated wire filament

6. a cold solid material containing only one type of atom

7. a star

Answer 1

There are two basic types of spectra .1.continous spectrum

2.discrete spectrum.continous spectrum is produced mainly hot dense objects like planets,stars,moon.these continuous spectra from these kind of objects is called thermal spectrum because hot dense objects will emit electromagnetic radiation at all wavelengths.

Discrete spectrum is produced by cooler thin gas in the upper layers of stars absorbing certain colours produced by hot dense lower layers.

So option 1 is correct