Which of the following compounds has the highest oxygen content by weight?

The molecular weight is 18, and 16 of that is oxygen.  

So, water is 16/18 * 100 = 88.9% oxygen by weight.  

None of the other compounds have as high an oxygen content (by weight) as water.  

This is a trick question, and the University Chemistry grad fell for it.  

If you have the same weight of each compound (let's say, 10 grams, for example), then H2O has the most oxygen weight (8.89 g).

while cooking a piece of 1/2 pound beef steak, a cast iron pan (2.4kg in weight) was heated 260 celsius.