What does the given structural formula represent?

For any integer $n \geq 1$,the sum $\sum_{k=1}^n k(k+2)$ is equal to

The greatest threat to genetic diversity in agricultural crops is

If $\alpha = \frac{5}{2! 3} + \frac{5 \cdot 7}{3! 3^2} + \frac{5 \cdot 7 \cdot 9}{4! 3^3} + \ldots$,then $\alpha^2 + 4\alpha$ is equal to

$A$ $x : 1$ molar mixture of $He$ and $CH_4$ is contained in a vessel at $20 \ bar$ pressure. Due to a hole in the vessel,the gas mixture leaks out. If the composition of the mixture effusing out initially is $8 : 1$,then the value of $x$ will be

The separation of a racemic mixture into pure enantiomers is termed as