Which of the following statements is true? -neon is inert because its outermost shell is complete. -nitrogen is inert because its outermost shell has eight electrons. -oxygen is more reactive than fluorine because oxygen needs only one electron to fill its outermost shell. -fluorine is more reactive than neon because fluorine has to lose only one electron to fill its outermost shell.

The correct answer is : Neon is inert because its outermost shell is complete.
Ne atomic number is 10 and has an electronic configuration of 1s² 2s² 2p⁶.The outer shell is complete therefore Ne is inert, in other words inactive as its very stable with a complete outer shell.

Nitrogen is not inert as its atomic number is 7 and electronic configuration is 1s² 2s² 2p³. therefore valence electrons are 5, it needs 3 more electrons to gain the complete outer shell configuration. Therefore this statement is incorrect.

F has 7 valence electrons and needs only one more electron to complete its outer shell whereas O has 6 valence electrons and needs 2 electrons to complete its outer shell. Since F only needs one electron and O needs two electrons, F is more reactive than O therefore third statement is incorrect 

F is more reactive than Ne as Ne is inert, however F needs to gain one electron and not lose, to fill its outermost shell therefore this statement too is incorrect