2. because oxygen is more electronegative than hydrogen, the electrons in a water molecule spend more time closer to

Explanation:

Electronegativity measures the relative strength with which the different elements attract the electrons in a covalent bond.

So, being oxygen more electronegative than hydrogen, the electrons in a water molecule (H₂O or H - O - H) are more strongly attractet by the oxygen atoms, which means that the electrons will spend more time closer to oxygen atoms than to hydrogen atoms.

As result of the electrons spending more time closer to the oxygen atoms, there will exist a partial negative charge over the oxygen atoms whiile there will be a partial positive charge over the hydrogen atoms.

Hence, the bond formed between oxygen and hydrogen atoms in a water molecules is a polar covalent bond.

You can read more about electronegativity and polar covalen bonds on link.

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.