Answer:
A 3.0 M solution of NaOH has 3.0 moles of NaOH per liter of solution. There are 0.25 L of solution (250mL⋅1L1000mL), so there are 0.25L⋅3.0mol/L=0.75mol of NaOH. The molar mass of NaOH is 40.0 g/mol, so there are 0.75mol⋅40.0g/mol=30g of NaOH, 30.
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