question_answer

Two elements A and B contain equal number of protons, electrons and neutrons. B contains double the number of electrons, protons and neutrons than in A. A contains 8 electrons in L-shell, B contains 2 electrons in N-shell. Identify A and B.

Answer:

Given: No. of electrons in A = No. of protons in A = No. of neutrons in \[A=x\] No. of electrons in B = No. of protons in B = No. of neutrons in\[B=y\] But\[y=2x\]. EC of A = 2, 8 (as it contains 8 electrons in L shell) \[\therefore \] The no. of electrons in A,\[x=10\] \[\Rightarrow \]No. of protons in A = No. of neutrons in\[A=x=10\]. Therefore A is Neon. We know that\[y=2x=20\]. \[\Rightarrow \]No. of proton in\[B=y=20\] Hence, B is calcium.