Which valve is located between the right atrium and the right ventricle?

In a unilocular ovary with a single ovule,the placentation is

$A$ transverse wave is travelling along a stretched string from right to left. The figure shown represents the shape of the string at a given instant. At this instant,

In a biprism experiment,if the $5^{\text{th}}$ bright band with wavelength $\lambda_{1}$ coincides with the $6^{\text{th}}$ dark band with wavelength $\lambda_{2}$,then the ratio $\left(\frac{\lambda_{2}}{\lambda_{1}}\right)$ is:

At $T(K)$,$100 \ L$ of dry oxygen is present in a sealed container. It is subjected to silent electric discharge,till the volumes of oxygen and ozone become equal. What is the volume (in litres) of ozone formed at $T(K)$?

Which of the following anthropogenic actions leads to evolution?