The quantum number which explains the line spectra observed as doublets in the case of hydrogen and alkali metals and doublets and triplets in the case of alkaline earth metals is

Two loops $P$ and $Q$ are made from a uniform wire. The radii of $P$ and $Q$ are $r_1$ and $r_2$ respectively,and their moments of inertia are $I_1$ and $I_2$ respectively. If $\frac{I_2}{I_1} = 4$,then $\frac{r_2}{r_1}$ equals:

The recessive genes located on the $X$-chromosome in humans are always:

If in a $\triangle ABC$,$\frac{1}{a+c} + \frac{1}{b+c} = \frac{3}{a+b+c}$,then $\angle C$ is equal to (in $^{\circ}$)

Which of the following is associated with the conservation of forests?

Which of the products is formed when acetone is reacted with barium hydroxide solution?