Out of $30$ points in a plane,$8$ of them are collinear. The number of straight lines that can be formed by joining these points is:

Which of the following molecules has the maximum dipole moment?

Which one of the following is not a biopolymer?

The period of $\sin ^4 x + \cos ^4 x$ is

If $\overrightarrow{a} = 2\widehat{i} - \widehat{j} + \widehat{k}$,$\overrightarrow{b} = \widehat{i} + \widehat{j} - 2\widehat{k}$ and $\overrightarrow{c} = \widehat{i} + 3\widehat{j} - (\lambda^2 + 3\lambda)\widehat{k}$ (where $\lambda$ is a constant) and $\overrightarrow{a}$ is perpendicular to $\overrightarrow{c} - \lambda\overrightarrow{b}$,then the sum of different values of $\lambda$ is:

If three unit vectors $\overrightarrow{a}, \overrightarrow{b}, \overrightarrow{c}$ satisfy $\overrightarrow{a}+\overrightarrow{b}+\overrightarrow{c}=\overrightarrow{0}$, then the angle between $\overrightarrow{a}$ and $\overrightarrow{b}$ is