PLEASE HELP!! I NEED ANSWER BEFORE MIDNIGHT!!
From the formula Al(NO3)3 we understand that there are 9 oxygen atoms in one Al(NO3)3 compound.
if 1mol → 9 mol
Then , 5.2510-3 mol → 9 5.25*10-3 mol
One mole is 6.022*10-23(Avogadro's number). So multiply it with Avogadro'a number to get your answer.
One unit of Al(NO3)3 has 9 O atoms. There are 3.16 x 10+21 of the said unit in the given mol. Multiply this by 9 to get the number of O atoms in 5.25 x 10-3 mol, which is 2.85 x 10+22.Source(s): books