Answer:
Number of aluminum atoms=4.457e23
Explanation:
First we will convert mass of aluminium into number of moles
27 grams of aluminium is equal to 1 mole of aluminium
1 grams of aluminium is equal to (1/27) mole of aluminium
20 grams of aluminium is equal to (20/27) mole of aluminium
20 grams of aluminium is equal to 0.740 mole of aluminium
Now to find number of aluminum atoms ,multiply number of moles of aluminium with Avogaro number(6.023e23)
number of aluminum atoms=0.740(6.023e23)
number of aluminum atoms=4.457e23
