What is the final product $(B)$ of this sequence?

$A$ body is thrown vertically upwards and reaches its maximum height in $t$ seconds. The total time from the time of projection to reach a point at half of its maximum height while returning (in seconds) is:

Consumption of which one of the following foods can prevent the kind of blindness associated with vitamin-$A$ deficiency?

Explain why alkyl groups act as electron donors when attached to a $\pi$ system.

The length of the subtangent at any point $(x_1, y_1)$ on the curve $y=5^x$ is

If $\vec{a} = \hat{i} - \hat{j} - \hat{k}$ and $\vec{b} = \lambda\hat{i} - 3\hat{j} + \hat{k}$ and the orthogonal projection of $\vec{b}$ on $\vec{a}$ is $\frac{4}{3}(\hat{i} - \hat{j} - \hat{k})$,then $\lambda$ is equal to: