Question

The number of gram-molecules (moles) of oxygen present in 6.02 x 10²⁴ molecules of CO is:

• A. 1
• B. 0.5
• C. 5
• D. 10

Hint:

First find moles of CO using Avogadro's number, then count oxygen atoms using the 1:1 ratio in CO.

Answer 1

The Correct Option is D

Step 1: One mole of any substance contains Avogadro's number of particles, \(N_A = 6.022 \times 10^{23}\).

Step 2: Number of moles of CO given is calculated by dividing the given number of molecules by Avogadro's number.

\[\text{moles of CO} = \frac{6.02 \times 10^{24}}{6.02 \times 10^{23}} = 10 \text{ moles}\]

Step 3: The formula of carbon monoxide is CO, which means every single molecule of CO is built from exactly one carbon atom and one oxygen atom.

Step 4: Since the ratio of oxygen atoms to CO molecules is 1:1, the number of moles of oxygen (atoms) present must equal the number of moles of CO.

\[\text{moles of oxygen} = 10 \text{ moles of CO} \times 1 = 10 \text{ moles}\]

Step 5: So the number of gram-molecules of oxygen present is 10, option D.