# Bharat Electronics (BEL) Core CS Questions with Answers

8 previously-asked core cs questions from Bharat Electronics (BEL)'s hiring process, each with the correct answer and a worked explanation. Written against the company's actual test pattern.

_Source: Astra (https://useastra.in). Updated 2026-09-05._

### 1. Which logic gate outputs 1 only when its two inputs are different?

A. XOR
B. AND
C. OR
D. NAND

**Answer:** XOR

**Explanation:** An XOR gate outputs 1 when the inputs differ and 0 when they are the same.

### 2. What is the decimal value of the binary number 1111?

A. 15
B. 16
C. 14
D. 13

**Answer:** 15

**Explanation:** 1111 in binary is 8 + 4 + 2 + 1 = 15.

### 3. How many bits are there in one byte?

A. 8
B. 4
C. 16
D. 2

**Answer:** 8

**Explanation:** One byte consists of 8 bits.

### 4. What is the result of the Boolean expression A AND (NOT A)?

A. 0
B. 1
C. A
D. NOT A

**Answer:** 0

**Explanation:** A and its complement can never both be true, so the AND is always 0.

### 5. A flip-flop can store how much data?

A. 1 bit
B. 1 byte
C. 8 bits
D. Nothing

**Answer:** 1 bit

**Explanation:** A single flip-flop is a basic memory element that stores one bit.

### 6. Which unit of a CPU performs arithmetic and logic operations?

A. ALU
B. RAM
C. ROM
D. Cache

**Answer:** ALU

**Explanation:** The Arithmetic Logic Unit (ALU) performs arithmetic and logic operations.

### 7. What is the binary representation of the decimal number 255?

A. 11111111
B. 10000000
C. 11110000
D. 11111110

**Answer:** 11111111

**Explanation:** 255 is 2 to the 8 minus 1, which is eight ones: 11111111.

### 8. Which number system uses base 16?

A. Binary
B. Octal
C. Decimal
D. Hexadecimal

**Answer:** Hexadecimal

**Explanation:** Hexadecimal uses base 16 with digits 0 to 9 and A to F.

More Bharat Electronics (BEL) preparation, including the full recruitment process: https://useastra.in/campus/bel