Answer :

So,

To find the number of moles in 90g of NaOH, what we do is to divide the given amount by the molar mass of NaOH.

The molar mass of NaOH is 40g/mol.

So,

[tex]\frac{90gNaOH}{\frac{40gNaOH}{mol}}=2.25\text{ moles of NaOH}[/tex]

Therefore, the correct answer is A. 2.25moles