select the correct answer. a certain compound has an empirical formula of ch₃. what must be true about this…

select the correct answer. a certain compound has an empirical formula of ch₃. what must be true about this compound? a. it contains three times as many hydrogen atoms as carbon atoms. b. it consists of 75% hydrogen by mass. c. each molecule contains exactly four atoms. d. each carbon atom is bonded to three hydrogen atoms.

select the correct answer. a certain compound has an empirical formula of ch₃. what must be true about this compound? a. it contains three times as many hydrogen atoms as carbon atoms. b. it consists of 75% hydrogen by mass. c. each molecule contains exactly four atoms. d. each carbon atom is bonded to three hydrogen atoms.

Answer

Answer:

A. It contains three times as many hydrogen atoms as carbon atoms.

Explanation:

Step1: Analyze empirical formula meaning

The empirical formula $CH_3$ shows the simplest - whole - number ratio of atoms in the compound. Here, for every 1 carbon atom, there are 3 hydrogen atoms.

Step2: Check option A

Since the ratio of $H$ to $C$ is 3:1 in the empirical formula $CH_3$, it contains three times as many hydrogen atoms as carbon atoms. This option is correct.

Step3: Check option B

The molar mass of $C$ is approximately $12\ g/mol$ and of $H$ is approximately $1\ g/mol$. In $CH_3$, the mass percentage of $H=\frac{3\times1}{12 + 3\times1}\times100%=\frac{3}{15}\times100% = 20%$, not 75%. So this option is incorrect.

Step4: Check option C

The empirical formula gives the simplest ratio, not the exact number of atoms in a molecule. The molecular formula could be $(CH_3)_n$ where $n$ is a positive integer. So we can't say each molecule contains exactly four atoms. This option is incorrect.

Step5: Check option D

The empirical formula does not give information about the bonding structure. It just gives the atom - ratio. So we can't say each carbon atom is bonded to three hydrogen atoms. This option is incorrect.