Water vapor, nitrogen, oxygen, carbon dioxide, helium, argon, and neon
Hope I helped a bit
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<u>Answer:</u> The given statement is true.
<u>Explanation:</u>
For the reaction to be spontaneous, the Gibbs free energy of the reaction must come out to be negative.
The equation used to calculate Gibbs free energy follows:
Exothermic reactions are defined as the reactions in which energy is released in the form of heat. The enthalpy change 
of the reaction comes out to be negative for this kind of reaction.
Entropy change is defined as the change in the measure of randomness in the reaction. It is represented as 
. Randomness of gaseous particles is more than that of liquid which is further more than that of solids.
We are given:
A solid substance is converting into a gaseous substance.
As, the entropy is increasing. So, the entropy change is positive.
Thus, the above reaction is spontaneous.
Hence, the given statement is true.
Q is the heat added to the system.
Answer:
1. In an atom, electrons (negatively charged) revolve around the positively charged nucleus in a definite circular path called as orbits or shells.
2. Each orbit or shell has a fixed energy and these circular orbits are known as orbital shells.
3. The energy levels are represented by an integer (n=1, 2, 3…) known as the quantum number. This range of quantum number starts from nucleus side with n=1 having the lowest energy level. The orbits n=1, 2, 3, 4… are assigned as K, L, M, N…. shells and when an electron attains the lowest energy level it is said to be in the ground state.
4. The electrons in an atom move from a lower energy level to a higher energy level by gaining the required energy and an electron moves from a higher energy level to lower energy level by losing energy.
Explanation:
