Calculate number of moles in 86.4 g of Ni

Number of moles = mass of Ni / molecular mass of Ni

mass of nickel = 86.4 g

molecular mass of nickel = 58.69

number of moles of Ni in 86.4 g

=86.4/58.69

=1.472 mol

(rounded to four significant figures instead of three because the first digit of the answer starts with a 1).