Element x is in the second period of the Periodic Table. An atom of element y has six more
protons than an atom of element x. Which statement must be correct?

A Elements x and y are in the same period of the table.
B Elements x and y have the same number of electrons in the first shell.
C Element y has six more electrons in its outer shell than does element x.
D The nucleon number of element y is six more than that of element x.

Answer:

2) B

This is quite an obvious answer. The answer is only asking for 1 statement which is correct. We know that ‘x’ is in period 2. This means that it has 2 shells with the first being completely full. Since, ‘y’ has six more electrons, it must have more than 1 shell as well. This means its first shell must also be full. First shell of any atom can only contain 2 electrons. Therefore, both ‘x’ and ‘y’ must have 2 electrons their first shells. Hence, they have the same number of electrons in the first shell.