Let $u=($:$2,6,3$:$)$ and $v=($:$1,2,-2$:$).$ Then $|u-v|=$

A$.\sqrt[\phantom{2}]{26}$

B$.10$

C$.\sqrt[\phantom{2}]{42}$

D$.4$

Let $u=($:$1,2,5$:$).$ Which of the following vectors is orthogonal to $u?$

A$.($:$-1,3,1$:$)$

B$.($:$1,-3,1$:$)$

C$.($:$1,3,-1$:$)$

D$.($:$1,3,1$:$)$

The angle between the vectors $2i-j+2k$ and $i+k$ equals

A$.co{s}^{-1}(\frac{1}{\sqrt[\phantom{2}]{3}\sqrt[\phantom{2}]{2}})$

B$.co{s}^{-1}(\frac{1}{3\sqrt[\phantom{2}]{2}})$

C$.co{s}^{-1}(\frac{4}{3\sqrt[\phantom{2}]{2}})$

D$.co{s}^{-1}(\frac{4}{\sqrt[\phantom{2}]{3}\sqrt[\phantom{2}]{2}})$

Let $u=2i-k$ and $v=2i+3j+k.$ Then $uv=$

A$.3i+5j+6k$

B$.3i+4j+6k$

C$.3i-5j+6k$

D$.3i-4j+6k$

$2$