Question

1. how many molecules are in 0.25 mole of o₂?

options:
1.5 × 10²³
3.0 × 10²³
6.0 × 10²³
1.2 × 10²⁴
clear all

Explanation:

Step1: Recall Avogadro's number

Avogadro's number is \( 6.02\times10^{23} \) molecules per mole (we can approximate it as \( 6.0\times10^{23} \) for simplicity here). The formula to find the number of molecules (\( N \)) is \( N = n\times N_A \), where \( n \) is the number of moles and \( N_A \) is Avogadro's number.

Step2: Substitute the values

Given \( n = 0.25 \) mole and \( N_A = 6.0\times10^{23} \) molecules/mole. So, \( N = 0.25\times6.0\times10^{23} \).

Step3: Calculate the result

\( 0.25\times6.0 = 1.5 \), so \( N = 1.5\times10^{23} \) molecules.

Answer:

\( 1.5\times10^{23} \) (the first option: \( 1.5\times10^{23} \))