A sample of sodium hydroxide (NaOH) has a mass of 160.0 g. The molar mass of NaOH is 40.00 g/mol. How many moles of NaOH does this sample contain?

To find the amount in moles, divide the sample’s mass by the molar mass: 160.0 g ÷ 40.00 g/mol = 4.000 mol. Therefore, the sample contains 4.000 moles of NaOH, which is choice A.

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