Which of the following compounds is the least ionic?

One mole of an ideal diatomic gas undergoes a transition from $A$ to $B$ along a path $AB$ as shown in the figure. The change in internal energy of the gas during the transition is:

If $\alpha = \frac{5}{2! 3} + \frac{5 \cdot 7}{3! 3^2} + \frac{5 \cdot 7 \cdot 9}{4! 3^3} + \ldots$,then $\alpha^2 + 4\alpha$ is equal to

If the position vectors of the vertices of a triangle are $2 \hat{i}-\hat{j}+\hat{k}$, $\hat{i}-3 \hat{j}-5 \hat{k}$, and $3 \hat{i}-4 \hat{j}-4 \hat{k}$, then the triangle is

The length of the latus rectum of the parabola $y^2+8x-2y+17=0$ is