To determine which planet would have a diameter of approximately 12 cm in this scale model where 1 cm equals 10,000 kilometers, we need to convert the diameter from centimeters to kilometers.
The formula to calculate the diameter in kilometers based on the scale is: \[ \text{Diameter in km} = \text{Diameter in cm} \times 10,000 \]
If the diameter of the model is 12 cm, then: \[ \text{Diameter in km} = 12 , \text{cm} \times 10,000 , \text{km/cm} = 120,000 , \text{km} \]
Now we can compare this value with the actual diameters of the planets:
- Earth: Approximately 12,742 km
- Mars: Approximately 6,779 km
- Jupiter: Approximately 139,822 km
- Saturn: Approximately 116,460 km
Given that 120,000 km is closest to Saturn's diameter (116,460 km) when we consider the options provided, the answer is:
Saturn