These Matrices Class 12 MCQ And Answers are most important for your upcoming examinations including JEE Main & JEE Advanced. These Matrices Class 12 MCQ And Answers will help you to score good marks in your exams by helping you to prepare the concepts better and hence, help you to understand the concepts more clearly.

## Matrices Class 12 MCQ And Answers

1. If A = then A² – 5A – 7I is

(A) zero matrix

(B) a diagonal matrix

(C) identity matrix

(D) None of these

**Answer:** a diagonal matrix

2. If A = then |2A| =

(A) 2|A|

(B) 4|A|

(C) 8|A|

(D) None of these

**Answer:** 4|A|

3.

(A) α = a² + b², β = ab

(B) α = a² + b², β = 2ab

(C) α = a² + b², β = a² – b²

(D) α = 2ab, β = a² + b²

**Answer:** α = a² + b², β = 2ab

4. If then the value of x, y is

(A) 3, 1

(B) 2, 3

(C) 2, 4

(D) 3, 3

**Answer:** 2, 3

5. If A is a m × n matrix such that AB and BA are both defined, then B is an

(A) m × n matrix

(B) n × m matrix

(C) n × n matrix

(D) m × m matrix

**Answer:** n × n matrix

6. If AB = A and BA = B, then

(A) B = 1

(B) A = I

(C) A² = A

(D) B² = I

**Answer:** A² = A

7. A square matrix A = [a_{ij}]_{n×n}is called a lower triangular matrix if a_{ij} = 0 for

(A) i = j

(B) i < j

(C) i > j

(D) None of these

**Answer:** i < j

8. The number of all possible matrices of order 3 × 3 with each entry 0 or 1 is

(A) 18

(B) 512

(C) 81

(D) None of these

**Answer:** 512

9. For any two matrices A and B, we have

(A) AB = BA

(B) AB ≠ BA

(C) AB = 0

(D) None of these

**Answer:** None of these

10. If A is a square matrix such that A² = I, then (A – I)³ + (A + I)³ – 7A is equal to

(A) A

(B) I – A

(C) I + A

(D) 3 A

**Answer:** A

11. If A is a matrix of order m × n and B is a matrix such that AB’ and B’A are both defined, then the order of matrix B is

(A) m × m

(B) n × n

(C) n × m

(D) m × n

**Answer:** m × n

12. If A and B are two matrices of the order 3 × m and 3 × n, respectively, and m = n, then the order of matrix (5A – 2B) is

(A) m × 3

(B) 3 × 3

(C) m × n

(D) 3 × n

**Answer:** 3 × n

13. For any unit matrix I

(A) I² = I

(B) |I| = 0

(C) |I| = 2

(D) |I| = 5

**Answer:** I² = I

14. A matrix A = [a_{ij}]_{m×n}is said to be skew symmetric if

(A) a_{ij} = 0

(B) a_{ij} = a_{ji}

(C) a_{ij} = -a_{ji}

(D) a_{ij} = 1

**Answer:** a_{ij} = a_{ji}

15. If A and B are square matrices then (AB)’ =

(A) B’A’

(B) A’B’

(C) AB’

(D) A’B’

**Answer:** B’A’

16. Let A be a non-singular matrix of the order 2 × 2 then |A^{-1}|=

(A) |A|

(B) 1/|A|

(C) 0

(D) 1

**Answer:** 1/|A|

17. If = 0, the value of x is

(A) 3

(B) 8

(C) 24

(D) 0

**Answer:** 8

18. If

(A) a unit matrix

(B) A

(C) a null matrix

(D) -A

**Answer:** a unit matrix

19. If A = then A + A^{T}= I if the value of x is

(A) π/6

(B) π/3

(C) π

(D) 0

**Answer:** π/3

20. The matrix is

(A) a symmetric matix

(B) a skew-sybtmetric matrix

(C) a diagonal matrix

(D) None of these

**Answer:** None of these