Question

Please help me what is the answer

Answer 1

There are 20.8 moles of propanol

Further explanation  

The mole is the number of particles(molecules, atoms, ions) contained in a substance  

1 mol = 6.02.10²³ particles

Can be formulated

N=n x No

N = number of particles

n = mol

No = Avogadro's = 6.02.10²³

1.2 x 10⁵ molecules of propanol

$\tt \dfrac{1.25\times 10^{25}}{6.02\times 10^{23}}=20.8~moles$