Answer:
Amount remaining = 1.205 * 10²⁴ molecules of urea
Explanation:
The molecular formula of urea is CH₄N₂O. It has a molar mass of 60 g/mol.
Number of moles of urea present in 150 g of urea = mass/molar mass
Number of moles = 150 g/ 60 g/mol = 2.5 moles of urea
I mole of urea contains 6.02 * 10²³ molecules of urea
2.5 moles of urea will contain 2.5 * 6.02 * 10²³ molecules of urea = 1.505 * 10²⁴ molecules of urea
If 3 * 10²³ molecules are removed from 1.505 * 10²⁴ molecules of urea, amount remaining will be:
1.05 * 10²⁴ - 3 * 10²³ = (15.05 - 3) * 10²³ molecules of urea
Amount remaining = 12.05 * 10²³
Amount remaining = 1.205 * 10²⁴ molecules of urea
