Three elements X , Y and Z have atomic numbers 19 , 37 and 55 respectively . Then the correct statements (s) is / are

Three elements X , Y and Z have atomic numbers 19 , 37 and 55 respectively . Then the correct statement (s) is / are

Elements X, Y and Z have atomic numbers 19, 37 and 55 respectively. Which of the following statements is true about them?

Elements X, Y and Z have atomic numbers 6, 9 and 12 respectively. Which one : forms a cation

Elements X, Y and Z have atomic numbers 6, 9 and 12 respectively. Which one : forms an anion

Three elements 'X', 'Y' and 'Z' have atomic numbers 18, 19 and 20 respectively. How many electrons are present in the M shell of these elements?