CBSE Board Examination 2026 · Section A · 1 mark

Q2: The order that cannot be a row matrix

The question

Which of the following cannot be the order of a row-matrix ?

(A) $2 \times 1$

(B) $1 \times 2$

(D) $1 \times n$

Exam answer

A row matrix has only one row, so its order is $1 \times n$ ⁠.

Why?

A matrix of order $m \times n$ has $m$ rows and $n$ columns. The first number always counts the rows.

A row matrix is a single row, such as $[\,4\ \ 7\ \ 1\,]$ ⁠, of order $1 \times 3$ ⁠.

$1 \times 2$ ⁠, $1 \times 1$ and $1 \times n$ each have one row, so (B), (C) and (D) can be row matrices.

A matrix of order $2 \times 1$ has two rows (it is a column matrix), so it is not a row matrix.

Why?

A $2 \times 1$ matrix has 2 rows and 1 column:

\begin{bmatrix} a \\ b \end{bmatrix}

Watch out: a $1 \times 1$ matrix such as $[5]$ is both a row matrix and a column matrix, so (C) is allowed.

Answer: (A) $2 \times 1$

Where this comes from

Chapter 3, Matrices: Types of matrices: row matrix.

Question type: One-mark MCQs

How to spot it: click to see

Type 6. One-mark MCQs: orders and definitions

Spot it: four options, asking when a sum or product is defined, what order it has, or what a word such as symmetric or inverse means.

Here: The word here is row matrix: it has one row, so its order is $1 \times n$ ⁠. A $2 \times 1$ matrix has two rows, so it cannot be one.

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