What is a Light Emitting Diode? Draw its circuit symbol.
A Light Emitting Diode (LED) is a semiconductor device that emits light when current flows through it in the forward direction. It operates based on the principle of electroluminescence, where electrons recombine with holes, releasing energy in the form of photons (light). The circuit symbol for an LED is:

Match the LIST-I with LIST-II
| LIST-I (Logic Gates) | LIST-II (Expressions) | ||
|---|---|---|---|
| A. | EX-OR | I. | \( A\bar{B} + \bar{A}B \) |
| B. | NAND | II. | \( A + B \) |
| C. | OR | III. | \( AB \) |
| D. | EX-NOR | IV. | \( \bar{A}\bar{B} + AB \) |
Choose the correct answer from the options given below:
Match List-I with List-II:
| List-I (Counters) | List-II (Delay/Number of States) |
|---|---|
| (A) n-bit ring counter | (I) Number of states is \( 2^n \) |
| (B) MOD-\(2^n\) asynchronous counter | (II) Fastest counter |
| (C) n-bit Johnson counter | (III) Number of used states is \( n \) |
| (D) Synchronous counter | (IV) Number of used states is \( 2n \) |
Choose the correct answer from the options given below:
A MOD 2 and a MOD 5 up-counter when cascaded together results in a MOD ______ counter.