question_answer 1)

  Comprehension given below is followed by   some multiple questions. Each question has one correct option. Choose the correct option: In the modem periodic table, elements are arranged in order of increasing atomic numbers which is related to the electronic configuration. Depending upon the type of orbitals receiving the last electron, the elements in the periodic table have been divided into four blocks, viz., \[s,\text{ }p,\text{ }d\]and\[f\], the modem periodic table consists 7 periods and 18 groups. Each period begins with filling of a new energy shell. In accordance with the Aufbau principle, the seven periods (1 to 7) have 2, 8, 8, 18, 18, 32 and 32 elements respectively. The seventh period is still incomplete. To avoid the periodic table being too long, the two series of f-block elements, called lanthanoids and actinoids are placed at the bottom of the main body of the periodic table. [A]          The element with atomic number 57 belongs to: (a) s-block                           (b) p-block                          (c) d-block                           (d) f-block   [B]          The last element of the p-block in 6th period is represented by the outermost electronic configuration: (a) \[7{{s}^{2}}7{{p}^{6}}\]                           (b) \[5{{f}^{14}}6{{d}^{10}}7{{s}^{2}}7{{p}^{6}}\]               (c) \[4{{f}^{14}}5{{d}^{10}}6{{s}^{2}}6{{p}^{6}}\]     (d) \[4{{f}^{14}}5{{d}^{10}}6{{s}^{2}}6{{p}^{4}}\]   [C]          Which of the elements whose atomic numbers are given below, cannot be accommodated in the present set up of the long form of the periodic table? (a) 107                                  (b) 118                                  (c) 126                                   (d) 102   [D]          The electronic configuration of the element which is just above the element with atomic number 43 in the same group is: (a) \[1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{5}}4{{s}^{2}}\]                                         (b) \[1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{5}}4{{s}^{2}}4{{p}^{6}}\] (c) \[1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{5}}4{{s}^{2}}\]                                         (d) \[1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{7}}4{{s}^{2}}\]   [E]          The elements with atomic numbers 35, 53 and 85 are all: (a) noble gases                 (b) halogens                       (c) heavy metals               (d) light metals

Answer:

  [B]?(c) In sixth period, the orbitals which are filled are: 6s 4f 5d and 6p [C]?(c) Long form of the periodic table can accommodate 118 elements. [D]?(a) The electronic configuration of the element with atomic number 43 is: \[1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{10}}4{{s}^{2}}4{{p}^{6}}4{{d}^{5}}5{{s}^{2}}\] It is a transition metal having 5 electrons in penultimate d-orbital. Thus, the element above this element has the following electronic configuration. \[1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{6}}3{{d}^{5}}4{{s}^{2}}\]