Which of the following is an essential amino acid?

The $24$ hour (diurnal) rhythm of our body,such as the sleep-wake cycle,is regulated by the hormone:

Male cockroach can be identified from the female by the presence of

Which one of the following pairs is incorrectly matched?

The dependence of disturbances due to two waves on time is shown in the figure. The ratio of their intensities $I_1 / I_2$ will be

Calculate the half-life of the first-order reaction $C_2H_4O_{(g)} \longrightarrow CH_{4(g)} + CO_{(g)}$. If the initial pressure of $C_2H_4O_{(g)}$ is $80 \ mm$ and the total pressure at the end of $20 \ minutes$ is $120 \ mm$,find the half-life in $\min$.