True or false a scientists opinion is a valid source of information to use in a scientific investigation?

If 22.5 liters of oxygen reacted with excess of hydrogen, how many liters of water vapor could be produced?

Given the following at 25c calculate delta hf for hcn (g) at 25c. 2nh3 (g) +3o2 (g) + 2ch4 (g) > 2hcn (g) + 6h2o (g) delta h rxn= -870.8 kj. delta hf=-80.3 kj/mol for nh3 (g), -74.6 kj/mol for ch4, and -241.8 kj/mol for h2o (g)

Estimate the molar mass of the gas that effuses at 1.6 times the effusion rate of carbon dioxide.