To convert 503.5 × 10⁻¹⁰ into scientific notation, we should express it in the form \( a \times 10^b \) where \( 1 \leq a < 10 \).
First, we can convert 503.5 into a number between 1 and 10:
503.5 can be written as \( 5.035 \times 10^2 \) (since \( 503.5 = 5.035 \times 100 \)).
Now we combine this with the original power of ten:
\( 503.5 \times 10^{-10} = 5.035 \times 10^2 \times 10^{-10} \).
When we multiply the powers of ten, we add the exponents:
\( 10^{2 + (-10)} = 10^{-8} \).
So, we have:
\( 503.5 \times 10^{-10} = 5.035 \times 10^{-8} \).
Thus, the correct answer is:
C. 5.035 × 10⁻⁸.