question_answer 103)

  Identify the pairs which are not of isotopes? (a) \[\,_{6}^{12}X,\,_{6}^{13}Y\]                               (b) \[\,_{17}^{35}X,\,_{17}^{37}Y\] (c) \[\,_{6}^{14}X,\,_{7}^{14}Y\]                               (d) \[\,_{4}^{8}X,\,_{5}^{8}Y\] 

Answer:

  (c, d) Isotopes have same atomic number but different mass number. \[\therefore \]\[(\,_{6}^{14}X,\,_{7}^{14}Y);(\,_{4}^{8}X,_{5}^{8}Y)\] are not isotopes.