Which one of the following pairs of molecules will have permanent dipole moments for both members

Which one of the following compounds has the smallest bond angle in its molecule?

The value of $$\mathop {\lim }\limits_{x \to 0} {{\int\limits_0^{{x^2}} {{{\sec }^2}tdt} } \over xsinx}$$ is

The function $$f\left( x \right)$$ $$ = \log \left( {x + \sqrt {{x^2} + 1} } \right)$$, is