IF THERE ARE THREE POSSIBLE VALUES FOR SPIN QUANTUM NUMBER, THEN POSSIBLE NUMBER OF ELEMENTS IN THE 5TH PERIOD OF PERIODIC TABLE WOULD BE-

In 5th period there are 5s, 4d and 5p orbital. s orbitals are 1 in number and p orbitals are 3 in number and d orbitals are 5 in number.
If the orbital contain 3 spin quantum number, then totally 27 elements are there.
5s = 1 x 3
4d =5 x 3
5p = 3 x 3
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    = 3 + 15 + 9 = 27