What can bias a scientists's observations

A bias is said to occur when a researcher influence the outcome of his experiments. Many things can bias a scientist observation.
A design bias may occur if the scientist did not take into consideration the inherent biases that are liable in the experiment he is performing.
Sampling bias may occur if the process of sapling introduces an inherent bias into the study; this may be in form of omission or inclusion.

1. o2(g)as a product

The answer should be vaporization