# NCERT Class 12-Mathematics: Exemplar Chapter – 3 Matrices Part 22 (For CBSE, ICSE, IAS, NET, NRA 2022)

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## Fill in the Blanks in Each of the Exercises 68 – 81

**Question 68**:

________ matrix is both symmetric and skew symmetric matrix.

**Answer**:

Null Matrix

**Question 69**:

Sum of two skew symmetric matrices is always ________ matrix.

**Answer**:

Skew symmetric matrix

**Question 70**:

The negative of a matrix is obtained by multiplying it by ________.

**Answer**:

**Question 71**:

The product of any matrix by the scalar ________ is the null matrix.

**Answer**:

**Question 72**:

A matrix which is not a square matrix is called a ________ matrix.

**Answer**:

Rectangular matrix

**Question 73**:

Matrix multiplication is ________ over addition.

**Answer**:

Distributive

**Question 74**:

If A is a symmetric matrix, then is a ________ matrix.

**Answer**:

Symmetrix matrix

**Question 75**:

If A is a skew symmetric matrix, then is a ________.

**Answer**:

Symmetrix matrix

**Question 76**:

If A and B are square matrices of the same order, then

(i) = ________.

(ii) ________. ( is any scalar)

(iii) = ________.

**Answer**:

(i) (ii) (iii)

**Question 77**:

If A is symmetric, then is a ________. ( is any scalar)

**Answer**:

Skew Symmetric matrix

**Question 78**:

If A and B are symmetric matrices, then

(i) is a ________.

(ii) is a ________.

**Answer**:

(i) Skew symmetric matrix

(ii) Neither symmetric nor skew symmetric matrix

**Question 79**:

If A is symmetric matrix, then is ________.

**Answer**:

Symmetric matrix

**Question 80**:

If A and B are symmetric matrices of same order, then AB is symmetric if and only if ________.

**Answer**:

AB = BA