The $K.E.$ and $P.E.$ of a particle executing $SHM$ with amplitude $A$ will be equal when its displacement is

The Lanthanoid contraction is responsible for the fact that

$A$ curve passes through the point $\left(1, \frac{\pi}{6}\right)$. Let the slope of the curve at each point $(x, y)$ be $\frac{y}{x}+\sec \left(\frac{y}{x}\right)$,$x>0$. Then the equation of the curve is

If $f: R \rightarrow R$ is an even function having derivatives of all orders,then which of the following is an odd function?

One mole of the complex compound $Co(NH_3)_5Cl_3$ gives $3$ moles of ions on dissolution in water. One mole of the same complex reacts with two moles of $AgNO_3$ solution to yield two moles of $AgCl_{(s)}$. The structure of the complex is :-