 Hello and welcome to the session. In this session we are going to discuss the following question and the question says that a mole of copper contains 6.02 into 10 raise to power 23 atoms. How many atoms are there in 0.635 moles? We are given a mole of copper contains 6.02 into 10 raise to power 23 atoms, that is one mole is equal to 6.02 into 10 raise to power 23 atoms, we have to find the number of atoms in 0.635 moles. So our first step is to identify initial and desired units. So here our initial unit is moles and desired unit is atoms. Our next step is to identify the unit path. We have to convert moles into atoms. So our unit path will look like where the initial quantity is 0.635 moles and the desired quantity will be in atoms. The next step is to write the unit path using equivalence as conversion factors to obtain desired unit. Now we know 1 mole is equal to 6.02 into 10 raise to power 23 atoms. So we have 1 mole upon 6.02 into 10 raise to power 23 atoms is equal to 1 or 6.02 into 10 raise to power 23 atoms upon 1 mole is equal to 1. We will choose those conversion factors so that the initial unit cancels out and we are left with the desired unit that is atoms. So we have the following unit path. Here we are using the conversion factor 6.02 into 10 raise to power 23 atoms upon 1 mole. The next step is to treat units as numbers to obtain answer. For this we cancel the units and terms so that we are left only with the desired units. So let us first cancel the units, moles cancel with mole and we obtain 0.635 into 6.02 into 10 raise to power 23 atoms which is equal to 3.8227 into 10 raise to power 23 atoms. So 0.635 moles of copper contains 3.8227 into 10 raise to power 23 atoms which is our required answer. This completes our session. Hope you enjoyed the session.