1. Name the following alkanes.

a. 2-methyl-propane.

b. 2-methyl-butane.

c. 4-ethyl-heptane.

d. 4-methyl-3-ethyl-heptane.

e. 3,3,5-trimethyl-heptane.

f. 2-dimethyl-butane.

g. 2-dimethyl-propane.

h. 3-diethyl-pentane.

Explanation:

Hello, for IUPAC rules, take into account that for numbering the organic chain, we must start by the carbon havinf the closest radical to it. Moreover, for naming, we can name alphabetically or by complexity order as shown below:

a. In this case, we consider the middled methyl as a radical in the three-carbon chain, therefore, IUPAC name is 2-methyl-propane.

b. In this case, we consider the methyl at the second carbon in the four-carbon chain (longest one), therefore IUPAC name is 2-methyl-butane.

c. In this case, we consider the ethyl at the fourth carbon in the seven-carbon chain (longest one), therefore IUPAC name is 4-ethyl-heptane.

d. In this case, we consider the ethyl at the third carbon and the methyl at the fourth carbon in the seven-carbon chain (longest one), therefore IUPAC name is 4-methyl-3-ethyl-heptane.

e. In this case, we consider the three at the third and fifth carbons in the seven-carbon chain (longest one), therefore IUPAC name is 3,3,5-trimethyl-heptane.

f. In this case, we consider the two methyles at the second carbon in the four-carbon chain (longest one), therefore IUPAC name is 2-dimethyl-butane.

g. In this case, we consider the two methyles at the second carbon in the three-carbon chain (longest one), therefore IUPAC name is 2-dimethyl-propane.

h. In this case, we consider the two ethyles at the third carbon in the five-carbon chain (longest one), therefore IUPAC name is 3-diethyl-pentane.

Best regards.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)