Which era is known as the age of birds and mammals?

Light waves producing interference have their amplitudes in the ratio $3: 2$. The intensity ratio of maximum and minimum of interference fringes is

Which alga exhibits a haplo-diplontic life cycle?

The value of $\left(\frac{1+\sin \frac{2 \pi}{9}+i \cos \frac{2 \pi}{9}}{1+\sin \frac{2 \pi}{9}-i \cos \frac{2 \pi}{9}}\right)^{3}$ is

$A$ neutral atom has $2, 8,$ and $7$ electrons in $K, L,$ and $M$ shells respectively. What is the total number of electrons in the $p$-orbitals?

The length of the transverse common tangent of the circles $x^2+y^2-2x+4y+4=0$ and $x^2+y^2+4x-2y+1=0$ is