Question

Identify the quantity of water (expressed in different terms) that contains highest number of water molecules in it.

• A. \(18\) mL of water
• B. \(10^{-3}\) mol of water
• C. \(0.18\) g of water
• D. \(0.00224\) L of water vapour at \(1\) atmp. and \(273\)K

Hint:

Convert every option into moles of water, since the number of molecules is proportional to the number of moles.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
The number of molecules is \(N=n\times N_A\), so the largest number of moles has the most molecules.

Step 2: Convert Each Option
(A) \(18\) mL of water has mass \(18\) g, so \(n=\dfrac{18}{18}=1\) mol.
(B) \(n=10^{-3}\) mol.
(C) \(n=\dfrac{0.18}{18}=0.01\) mol.
(D) \(n=\dfrac{0.00224}{22.4}=10^{-4}\) mol.

Step 3: Compare
The order is \(1>0.01>10^{-3}>10^{-4}\).

Step 4: Conclusion
Option (A) has the most moles and so the most molecules.

Final Answer:
18 mL of water contains the highest number of molecules. \[ \boxed{\text{(A) }18\text{ mL of water}} \]