compute the mole fraction of the solute and solvent in a 15%aquaeons nitric and (HNO3) solution?

Answer 1

Is that 15% w/w or w/v? If w/w, then
15% means 15 g HNO3 in 100 g solution or 15 g HNO3 in (15 g HNO3 + 85 g H2O).
Convert 15g HNO3 to moles. moles = grams/molar mass.
Convert 85 g H2O to moles.
Then XHNO3 = moles HNO3/total moles.
XH2O = moles H2O/total moles.
Post your work if you get stuck.