To solve the problem, we need to identify a hydrocarbon that meets two criteria: it does not decolorize alkaline KMnO4 solution and does not give any precipitate with ammoniacal silver nitrate (Tollens' reagent).
### Step-by-Step Solution:
1. **Understanding Alkaline KMnO4 Test**:
- Alkaline KMnO4 is a reagent used to test for unsaturation in hydrocarbons. Unsaturated hydrocarbons (like alkenes and alkynes) will decolorize the purple color of KMnO4 due to oxidation.
- Saturated hydrocarbons (like alkanes) do not react with KMnO4 and hence do not decolorize it.
2. **Understanding Ammoniacal Silver Nitrate (Tollens' Reagent)**:
- Tollens' reagent is used to detect aldehydes and terminal alkynes. When a terminal alkyne or an aldehyde is present, it will reduce the silver ion to metallic silver, resulting in a precipitate.
- Therefore, if a hydrocarbon does not give a precipitate with Tollens' reagent, it cannot be an aldehyde or a terminal alkyne.
3. **Identifying the Hydrocarbons**:
- Common hydrocarbons include:
- **Alkanes**: Saturated (e.g., methane, ethane, propane)
- **Alkenes**: Unsaturated (e.g., ethylene, propylene)
- **Alkynes**: Unsaturated (e.g., acetylene, propyne)
- **Aromatic hydrocarbons**: (e.g., benzene, toluene)
4. **Evaluating the Options**:
- **Benzene**: It is an aromatic hydrocarbon, which is saturated in terms of hydrogen atoms (does not have double or triple bonds). Therefore, it will not decolorize KMnO4 and will not react with Tollens' reagent.
- **Alkanes**: They also do not decolorize KMnO4 and do not react with Tollens' reagent.
- **Terminal Alkynes**: They will react with Tollens' reagent, giving a precipitate.
- **Alkenes**: They will decolorize KMnO4.
5. **Conclusion**:
- Among the hydrocarbons, benzene is the one that does not decolorize alkaline KMnO4 and does not give a precipitate with Tollens' reagent. Therefore, the answer is benzene.
### Final Answer:
The hydrocarbon which does not decolorize alkaline KMnO4 solution and also does not give any precipitate with ammoniacal silver nitrate is **Benzene**.
