To determine which planet would have a diameter of approximately 12 cm in the scale model where 1 cm equals 10,000 km, we first need to convert 12 cm back into kilometers using this scale.
12 cm x 10,000 km/cm = 120,000 km
Now we compare this with the actual diameters of the planets:
- Earth: approximately 12,742 km
- Jupiter: approximately 139,820 km
- Saturn: approximately 116,460 km
- Mars: approximately 6,779 km
The diameter of approximately 120,000 km most closely aligns with that of Saturn, which has a diameter of about 116,460 km.
Thus, the answer is:
Saturn