Which of the following compounds contains twice as many carbon atoms as oxygen atoms? Plz help :)

Iknow #2 is d. i just need to know why

If a molecule with a molecular formula of c13h18 is treated with an excess of h2 in the presence of finally divided pt metal under conditions required for maximum hydrogenation of the molecule to give a molecule with a formula c13h24, how many rings are in the molecule?

Structure of the atoms: discovery of the nucleus in 1909i need answering all of these questions