Which of the following pairs of organs includes only the endocrine glands?

Consider the following reaction: $N_{2(g)} + 3H_{2(g)} \longrightarrow 2NH_{3(g)}$. The rate of this reaction in terms of $N_2$ at $T \ K$ is $-\frac{d[N_2]}{dt} = 0.02 \ mol \ L^{-1} \ s^{-1}$. What is the value of $-\frac{d[H_2]}{dt}$ (in units of $mol \ L^{-1} \ s^{-1}$) at the same temperature?

The isothermal Bulk modulus of an ideal gas at pressure $P$ is

Assertion $(A)$: $NaCl$ is less soluble in heavy water than in ordinary water.
Reason $(R)$: Dielectric constant of ordinary water is more than that of heavy water.
The correct answer is

Which of the following is responsible for the conversion of milk into curd?

$A$ radioactive material decays by simultaneous emission of two particles with respective half-lives $1620 \, years$ and $810 \, years$. The time (in years) after which one-fourth of the material remains is: