Electronegativity generally increases across a period from left to right and decreases down a group.

1. Period 2 Elements: Carbon (C), Nitrogen (N), Oxygen (O), and Fluorine (F) are in the same period. The order of electronegativity increases as $C < N < O < F$ (Values: C=2.5, N=3.0, O=3.5, F=4.0).
2. Comparison with Silicon (Si): Silicon is in Group 14, below Carbon. Electronegativity decreases down a group, so $Si < C$ (Value for Si=1.8).

Combining these trends, the correct increasing order is $Si < C < N < O < F$.