Question

Which of the following statements is/are true for sterilization?

• A. Autoclaving at \(121^\circ C\) for \(20\) minutes destroys endospores
• B. Filtration through \(0.22\,\mu m\) membrane removes viruses from liquid
• C. Dry heat sterilization requires higher temperature and longer time than moist heat sterilization
• D. Gamma radiation sterilizes heat-sensitive medical equipment

Hint:

Moist heat sterilization is more efficient than dry heat sterilization because steam transfers heat more effectively and penetrates microorganisms better.

Answer 1

The Correct Option is A, C, D

Step 1: Understand sterilization.
Sterilization is the complete destruction or removal of all forms of microbial life, including bacterial endospores and viruses. Various physical and chemical methods are used for sterilization.

Step 2: Analyze autoclaving.
Autoclaving uses moist heat under pressure, commonly at
\[ 121^\circ C \] for about \(15\text{--}20\) minutes. This treatment effectively destroys bacterial endospores.
Hence, statement (A) is true.

Step 3: Analyze membrane filtration.
A \(0.22\,\mu m\) membrane filter is effective for removing most bacteria from liquids, but many viruses are much smaller and can pass through such filters.
Therefore, statement (B) is false.

Step 4: Compare dry heat and moist heat sterilization.
Dry heat sterilization is less efficient than moist heat sterilization because dry air penetrates poorly and transfers heat less effectively. Thus, it requires higher temperature and longer exposure time.
Hence, statement (C) is true.

Step 5: Analyze gamma radiation sterilization.
Gamma radiation is widely used for sterilizing disposable and heat-sensitive medical equipment such as syringes, catheters, and surgical gloves.
Hence, statement (D) is true.

Step 6: Identify all correct statements.
The true statements are:
\[ (A),\ (C)\ \text{and}\ (D) \]

Step 7: Final conclusion.
Therefore, the correct answer is
\[ \boxed{(A),\ (C)\ \text{and}\ (D)} \]