How many different input levels can be encoded by an analog-to-digital converter with 8-bit resolution?
Why An n-bit ADC produces an n-bit binary code word, and the number of distinct codes is 2^n. With 8 bits that is 2^8 = 256 discrete levels, numbered 0 through 255. Gain in the input amplifier only scales the analog voltage range that gets mapped onto those levels; it does not create or remove codes.
Watch out The choice that says 8 confuses the bit count with the level count, and the choices involving amplifier gain confuse resolution (number of steps) with input span (volts per step).
Levels = 2^bits. 8 bits = 256, 10 bits = 1024, 12 bits = 4096.