GK QUESTION#3155
Assertion (A): A neutral sodium atom in its ground state has the shell configuration 2,8,1.
Reason (R): A neutral sodium atom has 11 electrons, distributed as 2 in the first shell, 8 in the second and 1 in the third.
Choose the correct option.
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Answer
A. Both A and R are true, and R is the correct explanation of A
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Explanation
A neutral sodium atom has atomic number 11 and therefore 11 electrons. Its ground-state shell distribution is 2,8,1, so both statements are true and the reason identifies the configuration in the assertion. Neutrality and the ground state are required assumptions.