Ihave no idea how to answer question 5! someone !

Write the symbol for every chemical element that has atomic number greater than 3 and atomic mass less than 12.0 u.

In the 1800s, one of the statements in john dalton's atomic theory was that atoms are indivisible. later experimental evidence led to the discovery of subatomic particles such as neutrons, electrons, and protons. what happened to the indivisible atom part of dalton's atomic theory, and why?

If you have 5.25 grams of methane (ch4), how many grams of co2 will you produce ?