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

If $(2,-1,3)$ is the foot of the perpendicular drawn from the origin to the plane, then the equation of the plane is

The number of significant figures in $23.023$,$0.0003$,and $2.1 \times 10^{-3}$ are respectively:

An engine has an efficiency of $1/6$. When the temperature of the sink is reduced by $62^{\circ}C$,its efficiency is doubled. The temperature of the source is $.........^{\circ}C$.

$A$ body of mass $1\, kg$ is thrown upwards with a velocity $20\, m/s$. It momentarily comes to rest after attaining a height of $18\, m$. How much energy is lost due to air friction? $(g = 10\, m/s^2)$

In the leaf,vascular bundles are found in the