PART1 TUESDAY, January 7 2018-IN CLASS (d) are pigmented. 26 Select the t swer t
ID: 191195 • Letter: P
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PART1 TUESDAY, January 7 2018-IN CLASS (d) are pigmented. 26 Select the t swer that best completes the following statement: Chemical reactions in living an environment, within a narrow range of temperatures. systems occur in organic (c) extracellular (d) aqueous 27 Which subatomic particles contribute to the atomic number for any given element? protons and neutrons protons and electrons subatomic particles can vary between isotopes of the same element, without changing (a) protons (b) (c) neutrons (d) 28 Which the observed chemical properties? (a) electrons (b) protons and neutrons (c) neutrons (d) neutrons and electrons 29 Carbon 14 is an unstable isotope of carbon that decays very slowly. Compared to the common, stable carbon 12 isotope, carbon 14 has two additional (a) electrons. (b) neutrons. (c) protons. (d) ions. 30 Which of the following elements is least abundant in living organisms? (a) sulfur (b) carbon (c) oxygen (d) nitrogen The first task you are assigned in your summer laboratory job is to prepare a concentrated NaOH stock solution. The molecular weight of NaOH is 40. How many grams of solid Na0H w you need to weigh out to obtain a 500 mL. solution that has a concentration of 10 M? (a) 800 g (b) 200 g (c) 400g (d) 160g 31 32 A covalent bond between two atoms is formed as a result of the sharing of electrons. loss of electrons from both atoms. loss of a proton from one atom. transfer of electrons from one atom to the other. (a) (b) (c) (d)Explanation / Answer
26. B. Organic environment
27. A. Protons
28. C. Neutrons
29. B. Neutrons
30. A. Sulfur
31. B. 200g *10M = 10mol/l = 400g/l(1mole=40g NaOH) ; 200g for 500ml.
32. A. Sharing of electrons
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