What is the concentration of an electrolyte solution to have molar conductivity of $101 \Omega^{-1} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ and conductivity of $1.01 \times 10^{-2} \Omega^{-1} \mathrm{~cm}^{-1}$ at $298 \mathrm{~K} ?$

What is IUPAC name of following compound?

Which element from following is the last element of 5d-transition series?

The solubility of $\mathrm{CaCO}_3$ is $7 \times 10^{-5} \mathrm{~mol} \mathrm{dm}^{-3}$ at $25^{\circ} \mathrm{C}$. What is its solubility product at same temperature?