First find the no. of moles of NaOH :
<span>30/1000 = 0.3 dm3 so no. of moles = 0.3*0.5 = 0.15 moles </span>
<span>as NaOH reacts with HNO3 in a ratio of one to one, there must have been 0.15 moles of HNO3 too </span>
<span>moles/volume = concentration </span>
<span>volume= 15/1000 = 0.15 dm3 </span>
<span>concentration = 1.15/0.15 = 1 mol.dm-3 </span>
<span>The quicker way would be to realize that you used twice as much NaOH so the HNO3 had to be twice as strong</span>
Its B and D
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