Question

Resting potential of an axon is ___________ .

• A. -20 millivolts
• B. -70 millivolts
• C. +60 millivolts
• D. +140 millivolts

Hint:

In a resting neuron the inside is negative compared with the outside, about \(-70\) mV.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
At rest, the axon membrane is more permeable to \(\text{K}^+\) than \(\text{Na}^+\), so the inside is negatively charged.

Step 2: Value
The resting membrane potential of a typical axon is about \(-70\) mV.

Step 3: Compare the options
Positive values such as \(+60\) mV or \(+140\) mV belong to the action potential phase, not to rest.

Final Answer:
The resting potential of an axon is about -70 mV. \[ \boxed{\text{(B) }-70\ \text{millivolts}} \]