Question

Choose the correct relationship: molar mass - common name - chemical formula from the following options.

• A. $ 22.5 $-Ethyne-$ \text{C}_2\text{H}_2 $
• B. $ 292.5 $-Sulphur molecule-$ \text{S}_8 $
• C. $ 36.5 $-Hydrochloric acid-$ \text{HCl} $
• D. $ 65.5 $-Nitric acid-$ \text{HNO}_3 $

Hint:

To solve such problems, calculate the molar mass of the chemical formula provided and compare it with the given molar mass. Ensure that the common name and chemical formula correspond correctly.

Answer 1

The Correct Option is C

Step 1: Analyze Each Option.
Let's evaluate each option by calculating or verifying the molar mass, common name, and chemical formula: 1. Option (1): $22.5$ — Ethyne — $ \text{C}_2\text{H}_2 $
Ethyne (acetylene) has the chemical formula $ \text{C}_2\text{H}_2 $.
Molar mass: \[ (2 \times 12.01) + (2 \times 1.01) = 24.02 + 2.02 = 26.04 \, \text{g/mol} \] Given: $22.5$, which is incorrect. 2. Option (2): $292.5$ — Sulphur molecule — $ \text{S}_8 $
Molar mass: \[ 8 \times 32.07 = 256.56 \, \text{g/mol} \] Given: $292.5$, which is incorrect. 3. Option (3): $36.5$ — Hydrochloric acid — $ \text{HCl} $
Molar mass: \[ 1.01 + 35.45 = 36.46 \, \text{g/mol} \] Given: $36.5$, which is correct. 4. Option (4): $65.5$ — Nitric acid — $ \text{HNO}_3 $
Molar mass: \[ 1.01 + 14.01 + (3 \times 16.00) = 1.01 + 14.01 + 48.00 = 63.02 \, \text{g/mol} \] Given: $65.5$, which is incorrect. Step 2: Final Answer. \[ \boxed{(3) \quad 36.5 \text{-Hydrochloric acid-} \text{HCl}} \]