The question in the image asks:

"Why is the NAND gate called a universal building block? Explain it with a suitable example."

Answer:

A NAND gate is called a universal building block because any digital circuit or logic function can be constructed using only NAND gates. This includes all other basic logic gates such as AND, OR, NOT, NOR, and XOR. This ability to form any Boolean function makes the NAND gate a "universal" gate in digital electronics.

Example:

Let’s take the construction of a NOT gate (which inverts a signal) using just a NAND gate:

• In a NAND gate, if both inputs are the same (A = A), the output is the NOT of A. In Boolean terms, it works like this: $\text{NAND}(A, A) = \overline{A}$ This essentially mimics the behavior of a NOT gate.

Similarly, more complex logic gates like AND, OR, and XOR can be constructed using multiple NAND gates, proving its universality.

Would you like a detailed explanation of how to build other gates using NAND? Let me know!

Additional Questions:

1. How can a NOR gate also be used as a universal gate?
2. Can you explain how to create an AND gate using NAND gates?
3. What is the Boolean expression for a NAND gate?
4. Why is it advantageous to use universal gates in designing circuits?
5. Can you explain the difference between combinational and sequential circuits?

Tip: Remember that minimizing the number of gates in a circuit can improve its efficiency in terms of speed and power consumption.