General Science

To solve the problem, we need to classify the type of fuels to which coal, petroleum (oil), and natural gas belong.

1. Understanding Fossil Fuels:
Fossil fuels are formed from the remains of dead plants and animals that were buried under the Earth's surface millions of years ago. These organic materials underwent decomposition under high pressure and temperature to form:
- Coal (from plant material)
- Petroleum (crude oil)
- Natural gas

2. Elimination of Other Options:
- Chemical fuels: A vague term not specific to natural sources like coal or petroleum.
- Sunlight: A renewable source, not a fuel itself.
- Water: Not a fuel but a by-product in many combustion reactions.

Final Answer:
Coal, Petroleum (oil), and Natural Gas belong to

To solve the problem, we need to identify the plant from which natural rubber is obtained.

1. Source of Natural Rubber:
Natural rubber is obtained from the latex of the Hevea brasiliensis plant, commonly known as the rubber tree. This latex is a milky fluid that is collected and processed to produce rubber.

2. Evaluating the Options:
- Hevea brasiliensis: ✅ Correct source of natural rubber
- Jatropha: Used for biodiesel, not rubber
- Neem: Known for medicinal properties, not used for rubber
- Mimosa: Sensitive plant, not related to rubber production

Final Answer:
Rubber is prepared from the Hevea brasiliensis plant.

To solve the problem, we need to identify the person who discovered the stethoscope.

1. Understanding the Invention:
The stethoscope is a medical device used to listen to the internal sounds of a human or animal body, primarily for heart and lung sounds. It revolutionized diagnostics in medicine.

2. Historical Fact:
The stethoscope was invented in the year 1816 by Rene Laennec, a French physician. He created the device to avoid placing his ear directly on a patient's chest.

3. Eliminate Other Options:
- Linnaeus: Known for classification of organisms (taxonomy).
- Mendel: Known as the father of genetics.
- Maheswari: Known for contributions to plant embryology.

Final Answer:
Stethoscope was discovered by Rene Laennec.