31. The X +2 ion has 22 electrons, to determine its atomic number: a) 22 b) 24 c) 20 d) 18 e) 26 32. Which of the following is isoelectronic species? a) 12mg b) 13Al +3 c) 8AL-2 d) 11 to +1 e) 10Ne 33. For the atoms of different elements that have the same number of neutrons are called: a) isotopes. b) isotones.

c) isobars. d) isoelectronic. e) ions. 34. The sum of the mass numbers of two isotopes is 88 and half the sum of its neutrons is 24. Find the number of electrons one with charge +2. a) 22 b) 20 c) 18 d) 26 e) 24 35.

In two isobars atoms, their average nuclear charges is 19 and the average number of neutrons is 21. Find the mass number. a) 40 b) 50 c) 35 d) 30 e) 45 36. Calculate the number of fundamental subatomic particles for the ion: a) 200 b) 280 c) 283 d) 278 e) 189 37. The sum of the mass numbers of two isotopes is 60 and the difference of its neutrons is 4. Find the highest number of mass. a) 64 b) 32 c) 56 d) 28 e) 14 38. A divalent cation has a nuclear charge of +3,84.10-18C. How many electrons shows that cation? (E = -1,6.10-19 C) a) 20 b) 21 c) 22 d) 23 e) 24 39. Ion shown: What are isoelectronic? I. 15 P +3 II. 16S-2 III. 20 Ca2 + IV. 18Ar a) II and II b) II and III c) I and III d) II, III and IV e) All 40. The difference of the squares of the mass number and atomic number of a certain atom is 2580. If the number of neutrons is 30. Indicate the number of nucleons. a) 54 b) 28 c) 58 d) 46 e) 7 42. An atom of copper, with atomic number 29 and mass number 64, lost two electrons, then I. Its nuclear charge increases by 2. II. Ion atomic number is 27. III. The mass number does not varies. IV. The size of the electron cloud decreases. Are correct a) I and II b) II and III c) I and III d) III and IV e) All 43. A trivalent cation has a total of 77 fundamental subatomic particles: if the number of protons is in 5:6 ratio with the number of neutrons. Calculate the number of electrons in this ion. a) 20 b) 22 c) 25 d) 28 e) 32 44. A number of isotopes of some element has a sum of mass numbers equal to 173 and have a total of 95 neutrons. If the atomic number is less than 26. Calculate the number of isotopes. a) 3 b) 4 c) 5 d) 6 e) 8 45. An ion has a nuclear charge of +4.48 x 10-18C. If the area there 25 extranuclear electrons. Then the ion is an ………… a) divalent anion b) divalent c) trivalent anion d) and trivalent cation) monovalent anion