Number of electrons equals total charge divided by electron charge

Steps:

• Convert time to seconds: t = 10 × 3600 = 36,000 s.
• Compute total charge: Q = I × t = 0.5 × 36,000 = 18,000 C.
• Use electron charge: e = 1.6 × 10^{-19} C.
• Find electrons: N = Q / e = 18,000 / 1.6 × 10^{-19} = 1.125 × 10^{23}.

Why C is correct:

• Applies the formula N = (I t)/e from definition of current as charge flow rate, with t in seconds and e as elementary charge.

Why the others are wrong:

• A: Uses t ≈ 1 s without conversion, underestimating N.
• B: Calculates electrons per second only, ignoring full time.
• D: Applies formula with t = 10 s instead of hours, overestimating for short time.

Final answer: C