The correct option is 1 and 3 only.
Explanation
The atmosphere is a mixture of gases that surrounds the Earth, held in place by gravity. It plays a critical role in sustaining life and regulating the planet's physical environment.
- Statement 1 is Correct: The atmosphere contains gases essential for the survival of life forms. Oxygen is necessary for respiration in humans and animals, while carbon dioxide is vital for plants to perform photosynthesis.
- Statement 2 is Incorrect: The atmosphere does not allow harmful ultraviolet (UV) rays to reach the Earth freely. The ozone layer, located primarily in the stratosphere, absorbs the majority of the sun's harmful UV radiation, thereby protecting life on the surface from its damaging effects.
- Statement 3 is Correct: The atmosphere acts as a giant insulating blanket. Through the greenhouse effect (primarily due to carbon dioxide and water vapour), it traps terrestrial radiation and prevents the Earth from cooling down excessively at night, thus maintaining a temperature range suitable for life.
Key Takeaway: The atmosphere serves as a protective shield against UV radiation and acts as a thermal blanket to moderate Earth's temperature, in addition to providing essential gases like oxygen and carbon dioxide.