Which planet has a thick atmosphere of mainly hydrogen and helium due to conditions during the formation of the planets?
a. mercury
b. mars
c. neptune
d. venus

The planet that has a thick atmosphere of mainly hydrogen and helium due to conditions during the formation of the planets is option c. Neptune. Neptune' core is extremely hot and highly pressurized. It is mainly composed by hydrogen (80%) and helium (19%) and methane (1.5%). From the mixture of these gases comes the blue color of the planet.

answer; ///(positive correlation);

answer; i believe the answer is 80%, plz check first good luck;