(i) The outermost configuration of the element
= 2s2 2p4 (as it has 6 electrons in the outermost shell)
\(\therefore\) Electronic configuration of the element = 1s2 , 2s2 2p4
\(\therefore\) Atomic number = 2+ 2 + 4 = 8
Hence, the element is oxygen.
(ii) Element with Z = 107 has five, Z = 108 has six electrons while Z = 109 has seven 6d-eletrons. Hence, these elements differ in the number of electrons in the 6dsubshell.
(iii) Z = 86 Atomic number of next noble gas = 86 + 32 = 118 Its symbol is Uuo.