The conjugate base of $H_2PO_4^-$ is......

Which of the following substances is used in the laboratory to dry natural gas quickly?

Let $f: R \rightarrow R$ be a function such that $f(x)=x^3+x^2 f^{\prime}(1)+x f^{\prime \prime}(2)+6, x \in R$,then $f(2)$ is

The period of the function $f(\theta) = \sin \frac{\theta}{3} + \cos \frac{\theta}{2}$ is (in $\pi$)

If $\log 2=a, \log 3=b, \log 7=c$ and $6^x=7^{x+4}$,then $x$ is equal to:

$3.2$ moles of hydrogen iodide were heated in a sealed bulb at $444 \, ^oC$ until the equilibrium state was reached. Its degree of dissociation at this temperature was found to be $22 \%$. The number of moles of hydrogen iodide present at equilibrium are: