Which of the following statements is/are correct?

A.

n has a unique set of orthonormal basis vectors

B.

n does not have a unique set of orthonormal basis vectors

C.

Linearly independent vectors in n are orthonormal

D.

Orthonormal vectors in n  are linearly independent

Solution:

(A) Rn\mathbb{R}^n has a unique set of orthonormal basis vectors
Incorrect
There are infinitely many orthonormal bases in Rn\mathbb{R}^n. The Gram-Schmidt process can be applied to many different linearly independent sets to produce different orthonormal bases.

(B) Rn\mathbb{R}^n does not have a unique set of orthonormal basis vectors
Correct
As stated above, many orthonormal bases exist. So this statement is true.

(C) Linearly independent vectors in Rn\mathbb{R}^n are orthonormal
Incorrect
Linear independence does not imply orthonormality. For example, vectors [1,0][1, 0] and [1,1][1, 1] in R2\mathbb{R}^2 are linearly independent but not orthonormal.

(D) Orthonormal vectors in Rn\mathbb{R}^n are linearly independent
Correct
Any set of orthonormal vectors is automatically linearly independent by definition.