1 is hours and 2 is meters
D should be the correct answer. isotopes are atoms that have the same atomic number (number of protons) but different atomic masses (number of protons and neutrons). isotopes also have the same number of electrons since atoms need to have equal numbers of protons and electrons to not be considered ions. Since the number of protons determines the chemical properties of the atom, we can say that all isotopes have the same chemical properties due to the fact that all isotopes have the same atomic number.
I hope this helps. Let me know in the comments if anything is unclear.
There is a couple different ways to determine if a bond is ionic orcovalent. By definition, an ionicbond is between a metal and a nonmetal, and a covalent bond is between 2 nonmetals. So you usually just look at the periodic table and determine whether your compound is made of a metal/nonmetal or is just 2 nonmetals.
