How many molecules are in 0.25 mole of P4?

To find the number of molecules in 0.25 mole of P4, you can use Avogadro's number, which is approximately (6.022 \times 10^{23}) molecules per mole. Therefore, the calculation is (0.25 , \text{mole} \times 6.022 \times 10^{23} , \text{molecules/mole} \approx 1.5055 \times 10^{23}) molecules. Thus, there are approximately (1.51 \times 10^{23}) molecules in 0.25 mole of P4.