The approximate number of water molecules present in 9 gm of water is _____.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 3.011 × 1023 .
The approximate number of water molecules present in 9 grams of water is 3.011 × 10²³. To calculate this, we use the molar mass of water (H₂O), which is 18 grams per mole. So, 9 grams of water is 0.5 moles (9 ÷ 18 = 0.5). Using Avogadro’s number, which is 6.022 × 10²³ molecules per mole, we multiply:
0.5 × 6.022 × 10²³ = 3.011 × 10²³ molecules.
Thus, 9 grams of water contains approximately 3.011 × 10²³ water molecules, showing how vast the molecular scale is even in small quantities.