In the following $APs,$ find the missing term in the box: $2, \square, 26$

Are $\sqrt{3}, \sqrt{6}, \sqrt{9}, \sqrt{12}, \ldots$ in an $AP$? If they form an $AP$,find the common difference $d$ and write three more terms.

$A$ manufacturer of $TV$ sets produced $600$ sets in the third year and $700$ sets in the seventh year. Assuming that the production increases uniformly by a fixed number every year,find the production in the $10^{th}$ year.

In an $AP$ given $a_{n}=4, d=2, S_{n}=-14$,find $n$ and $a$.

For the $AP: \frac{3}{2}, \frac{1}{2}, -\frac{1}{2}, -\frac{3}{2}, \ldots,$ write the first term $a$ and the common difference $d$.

Which term of the $AP : 3, 8, 13, 18, \ldots$ is $78$ (in $^{th}$)?