Which of these characterizes organic compounds?

Let's analyze each question and provide the answers:

1. **Which of these characterizes organic compounds?**
- The only statement that characterizes organic compounds accurately is: **They are compounds containing carbon.**

2. **Which of these statements is FALSE?**
- The statement that is FALSE is: **Fire caused by kerosene can be put out if water is poured into the fire.** (This is false because water can spread a kerosene fire due to its lower density.)

3. **In which of the following medium would sound waves travel the fastest?**
- Sound waves travel fastest in: **Solids.** (Sound travels fastest in solids due to closely packed molecules that facilitate quicker vibrations.)

4. **Which of the following is heterogeneous?**
- The heterogeneous mixture is: **Sea water.** (Sea water contains various dissolved salts and other materials making it non-uniform.)

5. **Why should gasoline be stored in tightly covered narrow-mouthed containers and should be placed away from heat?**
- The primary reasons are: **To reduce evaporation** and **To decrease its potential as a fire hazard.**

Thus, the best answer to the last question is: **I and II.**

To summarize:
1. Organic compounds are characterized by containing carbon.
2. The false statement is about fire and water with kerosene.
3. Sound travels fastest in solids.
4. Sea water is heterogeneous.
5. Gasoline should be carefully stored to reduce evaporation and minimize fire hazards (I and II).