Question

Which of the given elements A B C D and E go with the atomic number 2 3 7 10 and 20 respectively belong to the same period

Answer 1

Answer:An element with atomic number 7 (b) An element with atomic number 3 (c) An element with atomic number 12 (d) An element with atomic number 19. Soln: Answer is (a) An element with atomic number 7. Explanation: Element with atomic number 7 has electron configuration 2,5 which means it can gain 3 electrons and is a electronegative element.

Explanation:Atomic configuration of : A:2,5. B:2,8. C:2,8,2. D:2,8,18 ,12,1. E:2,7. a) it looks like no two elements here have similar chemical properties because no two elements have same valence electrons. b)B is an inert gas as the outer shell of B is completely filled. c) C belongs to the third shell. Basically the number of shells = number of the period.