The study of homologous structures in mature organisms provides evidence for evolutionary relationships among certain groups of organisms. Which field of study includes this evidence of evolution?

In Young's double slit experiment,the seventh maximum with wavelength ${\lambda _1}$ is at a distance $d_1$ from the central maxima,and the same maximum with wavelength ${\lambda _2}$ is at a distance $d_2$. Then the ratio $d_1/d_2$ is:

The product is:

$A$ body of mass $1\,kg$ crosses a point $O$ with a velocity $60\,ms^{-1}.$ $A$ force of $10\,N$ directed towards $O$ begins to act on it. It will again cross $O$ in ........ $\sec$.

If $\sin {\theta _1} + \sin {\theta _2} + \sin {\theta _3} = 3,$ then $\cos {\theta _1} + \cos {\theta _2} + \cos {\theta _3} = $

$50 \, g$ of copper is heated to increase its temperature by $10 \, ^\circ C$. If the same quantity of heat is given to $10 \, g$ of water,the rise in its temperature is ........ $^\circ C$ (Specific heat of copper $= 420 \, J \cdot kg^{-1} \cdot ^\circ C^{-1}$,Specific heat of water $= 4200 \, J \cdot kg^{-1} \cdot ^\circ C^{-1}$)