The unit vector parallel to the resultant vector of $2i + 4j - 5k$ and $i + 2j + 3k$ is

Let $ABCDEF$ be a regular hexagon with the vertices $A, B, C, D, E, F$ in counter-clockwise order. If $O$ is the center of $ABCDEF$,then the vector $\vec{AO}$ is equal to which of the following?

If $D, E$ and $F$ are respectively the mid-points of $AB, AC$ and $BC$ in $\triangle ABC$,then $\overrightarrow{BE} + \overrightarrow{AF}$ is equal to :

If $L, M, N$ are the midpoints of the sides $PQ, QR$ and $RP$ of $\triangle PQR$ respectively,then $\overrightarrow{QM} + \overrightarrow{LN} + \overrightarrow{ML} + \overrightarrow{RN} - \overrightarrow{MN} - \overrightarrow{QL} = $

Classify the following as scalar or vector quantities:
Time period

Let $\alpha, \beta, \gamma$ be distinct real numbers. The points with position vectors $\alpha \hat{i} + \beta \hat{j} + \gamma \hat{k}$,$\beta \hat{i} + \gamma \hat{j} + \alpha \hat{k}$,and $\gamma \hat{i} + \alpha \hat{j} + \beta \hat{k}$: