Using the trends in the periodic table, rank the following atoms in order of increasing electronegativity.

K, Rb, H,
Br, F, Cl
C, O, F

Here is the order of increasing electronegativity for the given atoms:

K < Rb < H < C < Br < Cl < O < F

Explanation:
1. First, let's compare the electronegativity of K and Rb. Both are alkali metals, and as we move down a group in the periodic table, electronegativity decreases. Therefore, K has a lower electronegativity than Rb.
So, K < Rb.

2. Next, let's compare H with both K and Rb. Hydrogen (H) is not a metal and tends to have higher electronegativity than metals. Therefore, H has a higher electronegativity than both K and Rb.
So, K < Rb < H.

3. Now, let's compare Br, F, and Cl. All three are halogens, and as we move across a period in the periodic table, electronegativity generally increases. Therefore, Br has a lower electronegativity than Cl, and Cl has a lower electronegativity than F.
So, K < Rb < H < Br < Cl < F.

4. Finally, let's compare C, O, and F. As we move across a period in the periodic table, electronegativity generally increases. Therefore, C has a lower electronegativity than O, and O has a lower electronegativity than F.
So, K < Rb < H < C < Br < Cl < O < F.

Ranking the atoms in order of increasing electronegativity:
K < Rb < H < C < Br < Cl < O < F