Your calculations are mostly correct, but there are a couple of errors in your final answer. Let's go through the steps:
1. Calculate the moles of H2O2:
moles = mass / molar mass = 529,000 g / 34 g/mol = 15,558.82 mol
2. Calculate the heat released per mole of H2O2:
ΔHrxn = -196.1 kJ
Heat released per mole = -196.1 kJ / 2 mol = -98.05 kJ/mol
3. Calculate the total heat released:
Total heat released = moles of H2O2 × heat released per mole
Total heat released = 15,558.82 mol × -98.05 kJ/mol = -1,524,740.891 kJ
4. Round the answer to three significant figures:
-1,524,740.891 kJ rounded to three significant figures is -1.52 × 10^6 kJ
So, the correct answer is -1.52 × 10^6 kJ (rounded to three significant figures).