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Nuclei

Question
CBSEENPH12047982

An atom of mass number 15 and atomic number 7 captures an a-particle and then emits a proton. The mass number and atomic number of the resulting atom will be respectively

  • 14 and 12

  • 15 and 3

  • 16 and 4

  • 18 and 8

Solution

D.

18 and 8

          7X15  + 2He4  →   1H1  +  ZYA

                     Alpha        Proton
                     particle

According to the law of conservation of charge, we get

          7 + 2 = 1 + Z

⇒                Z = 8

According to the law of conservation of mass, we get

          15 + 4 = 1 + A

⇒             A = 18

Hence, the resulting atom has mass number 18  and  atomic number 8.