Which has the most thermal energy out of the following situations a) 100g of water at 20 °C
b)50g of water at 35°C
c)100g of water at 35°C
d) 100g of copper at 35°C

Yes you are correct use the scientific method

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom

Hope you find the answer

Ithink carbon dioxide, i am not completely sure.tell me if i am wrong.