questions 1-3 please

QUESTION 1 What requirement must be met before two electrons can exist in the same orbital under normal ground-state conditions? The electrons must have the same spins. The electrons must have opposite spins. The are no requirements of the electrons in an atom that is in its ground state. An orbital can only hold one electron at a time if the atom is in its ground state. QUESTION 2 A hydrogen atom contains electrons in a "2" sublevel. True False QUESTION 3 A sample of a certain compound contains 79.89% carbon and 20.11% hydrogen. How much carbon is in a 1.34 gram sample of this compound? O 20.11 grams of carbon O 168 grams of carbon O 79.89 grams of carbon O 1.07 grams of carbon