Step 1: Verify Statement-I.
The atomic radius is approximately
\[
10^{-10}\text{ m},
\]
while the nuclear radius is approximately
\[
10^{-15}\text{ m}.
\]
Therefore,
\[
\frac{\text{Atomic radius}}{\text{Nuclear radius}}
=
\frac{10^{-10}}{10^{-15}}
=
10^5.
\]
Hence, Statement-I is correct.
Step 2: Verify Statement-II.
According to Rutherford's nuclear model,
\[
\boxed{\text{Most of the mass is concentrated in the tiny nucleus,}}
\]
and therefore,
\[
\boxed{\text{most of the volume of an atom is empty space}.}
\]
Hence, Statement-II is also correct.
Step 3: Write the conclusion.
Both statements are correct.
Hence,
\[
\boxed{(A)}
\]
is the correct answer.