Classify the below substances based on their natural physical state (Solid or Gas).
Methane, Gold, Silver, Platinum
Solid - old, Silver, Platinum
Gas - Methane
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: Classify the below substances based on their natural physical state (Solid or Gas).
Methane, Gold, Silver, Platinum
### Input: 
### Response: Solid - old, Silver, Platinum
Gas - Methane