When hydrogen peroxide decomposes, what mass of
hydrogen peroxide is needed
in solution to produce 1.6 g of
oxygen gas?

The Molar mass of Oxygen is 32 g/mol

Therefore moles of Oxygen = 1.6/32 =0.05

2 H2O2 = 2 H2O + O2

So, 2 x 0.05 = 0.1 moles of peroxide are needed.

The molar mass of peroxide is 34 g/mol

Mass = moles x Mr = 0.1 x 34 = 3.4g

Although in reality the yield is unlikely to be 100% so a better answer would be “more than 3.4g”

i believe the answer is 5,000