Select the options that complete the following sentence. A star is: a giant ball of gas that produces heat and lightmade of solid rockheld together by gravitymade of heavy elements like lead and mercury

On the main sequence, stars obtain their energyGroup of answer choicesfrom nuclear fissionfrom gravitational contractionfrom chemical reactionsby converting helium to carbon, nitrogen and oxygenby converting hydrogen to helium

What type of energy is produced in a star?AfusionBelectricityCfissionDkinetic

Describe how the chemical composition of a star may be determined.

Select all of the options that complete the following sentence. A moon:is a natural satellitemust orbit a starmust orbit a planetmust have a thick atmosphere

Select the statement that is trueGroup of answer choicesAs the star exhausts its hydrogen, it begins lithium burning to fuse heavier nuclei to form increasingly larger atomsA gamma ray has energy, mass and chargeIn star formation, clouds of atomic hydrogen are pulled together by electrostatic attractionsAll atoms are generated from the simplest nuclide, hydrogen, by nuclear reactions