What causes a decrease in soil fertility?

$A$ - Events after the formation of zygote are called post-fertilization events.
$R$ - In viviparous animals,a young one develops outside the mother's body.

The coordination number and the oxidation state of the element $E$ in the complex $[E(en)_2(C_2O_4)]NO_2$ (where $en$ is ethylenediamine) are,respectively,

$CH_3CN \xrightarrow{Na + C_2H_5OH} X$. The compound $X$ is:

In an experiment of a simple pendulum, the errors in the measurement of length of the pendulum $(L)$ and time period $(T)$ are $3 \%$ and $2 \%$, respectively. The maximum percentage error in the value of $\frac{L}{T^2}$ is (in $\%$)

In the context of the lanthanoids,which of the following statements is not correct?