Choose the correct statement(s)
Statements
(i) O₃ in the stratosphere is not completely effective in shielding us from UV-B. (ii) UV-A is biologically least harmful. (iii) Chapman mechanism deals with only O₃ formation in the stratosphere. (iv) Sunscreen lotions either reflect or absorb or scatter UV-B and UV-A. (v) UV-B helps in dissociation of O₃ molecule in the stratosphere.
Choose the most appropriate answer from the options given below:

Correct option is B

Let's analyze each statement:
1. Statement (a):
· True. The ozone layer (O₃) in the stratosphere primarily absorbs UV-C and most UV-B, but it does not block all UV-B radiation completely.
2. Statement (b):
· True. UV-A is the least harmful form of UV radiation, although it still contributes to skin aging and damage over long exposure.
3. Statement (c):
· False. The Chapman mechanism deals with both the formation and destruction of ozone in the stratosphere, not just formation.
4. Statement (d):
· True. Sunscreen lotions protect by reflecting, absorbing, or scattering UV-B and UV-A radiation.
5. Statement (E):
· True. UV-B radiation helps in the dissociation (breaking down) of ozone molecules (O₃) in the stratosphere.
Therefore, the correct statements are (a), (b), (d), and (E).
Information Booster 1. Stratospheric Ozone (O₃):
· Forms a protective layer in the stratosphere that absorbs harmful UV radiation.
2. UV Radiation Types:
· UV-A: Least harmful, but prolonged exposure can cause skin damage.
· UV-B: Causes sunburn and skin cancer; partially blocked by the ozone layer.
· UV-C: Most harmful but is completely absorbed by the ozone layer.
3. Chapman Mechanism:
· Explains both the formation and breakdown of ozone:

4. Sunscreen Protection:
· Protects against both UV-A and UV-B radiation by using physical blockers (e.g., zinc oxide) or chemical absorbers.
5. Photodissociation of Ozone:
· UV-B radiation breaks down ozone into oxygen molecules and atoms, affecting the ozone balance.
Additional Knowledge · Statement (a): Ozone depletion can reduce the effectiveness of the ozone layer in blocking UV-B radiation.
· Statement (b): UV-A is responsible for skin aging and DNA damage over time, but it is less harmful compared to UV-B and UV-C.
· Statement (c): The Chapman mechanism is key to understanding ozone dynamics, including formation and destruction processes.
· Statement (d): Broad-spectrum sunscreens protect from both UV-A and UV-B, offering comprehensive protection.
· Statement (E): UV-B radiation is critical for maintaining the dynamic equilibrium of ozone in the stratosphere.