The compound insoluble in acetic acid is

Which of the following compound$(s)$ has '$Z$' configuration?

The area of the triangle formed by the lines ${y^2} - 9xy + 18{x^2} = 0$ and $y = 9$ is

Gymnosperms lack true fruits because .........

When an $AC$ source of $e.m.f. \ e = E_0 \sin(100t)$ is connected across a circuit,the phase difference between the $e.m.f. \ e$ and the current $i$ in the circuit is observed to be $\frac{\pi}{4}$ as shown in the diagram. If the circuit consists possibly only of $RC$,$RL$,or $LC$ in series,find the relationship between the two elements.

The oxidation state and covalency of $Al$ in $[AlCl(H_2O)_5]^{2+}$ are respectively