1. An isotope is an atom of an element that varies in mass number due to variation in the number of: (Points: 5)atoms.protons.neutrons.electrons.2. A covalent bond is: (Points: 5)the attraction that one atom has for another atom.the attraction between two atoms formed by the sharing of electrons.formed between the positive charge of a hydrogen atom in one molecule and the negative charge of anitrogen atom in another nearby molecule.the attraction between a positive ion and a negative ion.3. Solutions are always comprised of: (Points: 5)solvents and solute.liquids and solids.water and salts.compounds and ions.4. Which of the following is a chemical reaction that is also known as digestion? (Points: 5)PhosphorylationDehydration synthesisAcid-baseHydrolysis