A comb.

Your voice.

20, 22, 24, 26

2n + (2n + 2) + (2n + 4) + (2n + 6) = 92
8n + 12 = 92 => 8n = 80 => n = 10
2n = 20

5.
A = 50, B = 10.

Hands.

Charcoal.

1.5

acellular, acerbated, acerbates, acescence, acescency, acetabula, acetamide, acetified.

203
The pattern is x 2 + 1, x 2 - 1, x 2 + 1, x 2 - 1,..... So, missing term = 101 x 2 + 1 = 203.

OBLIGATE.

A pair of slippers.

Neither. Nine and seven equal sixteen.