Arrange the following substances in the order of increasing entropy at 25°C. a. HF(g)
b. NaF(s)
c. SiF 4(g)
d. SiH 4(g)
e. Al(s)

In solving this question it is important to note that entropy is referred to as the degree of randomness in a compound or system.

Entropy is highest in gas and lowest in solids

The order is given as:

Gas > Liquid > Solid

Another criteria is the more the elements in a compound, the more the entropy.

For example: KO3 has more entropy than KO2 due to the presence of more elements.

The last criteria is calculating their masses , the one with a greater mass has the higher entropy.

The option with the least entropy will be a solid. Al(s) and NaF(s) are both solids. NaF(s) has more elements in a compound which makes it have a higher entropy than Al(s). This means NaF(s) > Al(s).

The next to consider are the gaseous compounds which are HF(g) , SiF4(g) and SiH4(g). The least entropy will be HF(g) . This is because it has the least number of elements of the 3 compounds.

SiF4(g) and SiH4(g) have equal number of elements in a compound but the one with the highest mass is SiF4(g) because fluorine has a higher mass when compared to hydrogen. This means the compound with the highest entropy is SiF4(g).

The order of increasing entropy is given below:

Al(s) < NaF(s) < HF(g) < SiH4(g) < SiF4(g)

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be