Which of these species would you expect to have the highest standard entropy (S°)? a. CH4(g)
b. C2H2(g)
c. C2H4(g)
d. C2H6(g)
e. C3H8(g)

e. C₃H₈(g)

Explanation:

Standard entropy is the absolute  entropy of a substance at 1 atm and 25°C.

For  different substances in the same phase, molecular complexity determines which ones have higher entropies.

Consider the gases CH₄, C₂H₂, C₂H₄, C₂H₆, C₃H₈. Propane (C₃H₈) has a more complex structure and hence more ways to execute molecular motions, which also increase its microstates. Therefore,  propane has the greatest standard entropy.

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.