20) Which statement is NOT true about ionic bonds? A) An ionic bond occurs between positive ions and negative ions. B) Electrons are completely lost or gained in ion formation An ion has the same number of electrons as a nonionic atom of the same element. D) A salt such as NaCl is formed by an ionic reaction. 21) Which of the following would be a proposed mechanism by which stomach antacids work? A) Antacids are bases and by definition can absorb OH- out of a solution. B) Antacids are bases and by definition can absorb H+ out of a solution. C) Antacids dilute the solution, therefore lowering the pH. D) Antacids contain mostly water and so they neutralize the solution. 22) An atom's atomic mass is best described as the mass of A) protons and neutrons it contains. B) protons and electrons it contains. C) electrons in the outermost shell. D) the neutrons it contains. 23) Which of the following is/are an atom, an isotope and an ion? A) 2H or deuterium B) All of the choices are atoms, isotopes and ions. C) Hz or hydrogen gas D) H 24) Both 180 and 160 are found in nature. However, 160 is the most common. Therefore, A) 180 is the form of oxygen that provides living cells with life. B) only the common form of 160 can bond with hydrogen atoms to form H20. C) oxygen atoms can have eight or 10 neutrons. D) these are different elements. 25) An orbital is best described as A) the electron shell closest to the nucleus. B) the volume of space in which electrons are most often found. C) the original energy level of electrons in photosynthesis. D) the outermost electron shell of an atom. 26) Which element does not help makeup 95% of your body weight? A) potassium B) phosphorus C) nitrogen D) carbon
