Which of the following is not a property of vectors?

The vector having magnitude of $2 \sqrt{29}$ units in the direction of vector $\vec{a} = 4 \hat{i} + 3 \hat{j} - 2 \hat{k}$ is . . . . . . .

The position vectors of $A$ and $B$ are $2i - 9j - 4k$ and $6i - 3j + 8k$ respectively. Then the magnitude of $\overrightarrow{AB}$ is:

Find the centroid of the triangle whose vertices are $i + 2j, 2i + j, i + j + k$.

If the vectors $-3 \hat{i} + 4 \hat{j} + \lambda \hat{k}$ and $\mu \hat{i} + 8 \hat{j} + 6 \hat{k}$ are collinear, then $\lambda - \mu =$

If the position vectors of the points $A$ and $B$ are $\vec{a} = \hat{i} + 3\hat{j} - \hat{k}$ and $\vec{b} = 3\hat{i} - \hat{j} - 3\hat{k}$,then what will be the position vector of the midpoint of $AB$?