Which one of the following shows isogamy with non-flagellated gametes?

$A$ ball is allowed to fall from a height of $10\, m$. If there is $40\%$ loss of energy due to impact,then after one impact,the ball will rise to a height of ......... $m$.

As the atomic number increases,which of the following properties of alkali metals increases?

Which one of the following complexes will have four isomers?

$A$ rod of length $20 \, cm$ is made of metal $A$. It expands by $0.075 \, cm$ when its temperature is raised from $0^{\circ}C$ to $100^{\circ}C$. Another rod of a different metal $B$ having the same length expands by $0.045 \, cm$ for the same change in temperature. $A$ third rod of the same length is composed of two parts,one of metal $A$ and the other of metal $B$. This rod expands by $0.060 \, cm$ for the same change in temperature. The portion made of metal $A$ has the length ........ $cm$.

The solution of $\tan y \frac{dy}{dx} = \sin(x+y) + \sin(x-y)$ is