A 0.250 L bottle contains 75.0 mL of a 3.0% by mass solution of hydrogen peroxide (H2O2). How much will the pressure (in mm Hg) in the bottle incrase of the H2O2 decomposes to H2O (l) and O2 (g) at 34 degrees Celsius?

(Denisty of solution is 1.00g/mL and volume of liquid doesn't changue during dcomposition)

Answer: 2860 mm Hg

*I don't quite understand the information this question is giving me. So are they basically asking for the pressure the O2 gas is exerting? how i do calculate the difference in pressure?*

I realize that 75 mL of the solution contains 0.066 M of H2O2.

and Also, the decomposition equation is

H2O2= 2H2O+O2.

If anyone could help me or clarify the question, that'd be great.

thanks.