Which of the following is the strongest base?

In a metre bridge experiment,the ratio of the left gap resistance to the right gap resistance is $2:3$. The balance point from the left is: (in $~cm$)

$\int \frac{dx}{(x+1) \sqrt{4x+3}}$ is equal to

$SiCl_4$ on hydrolysis forms '$X$' and $HCl$. Compound '$X$' loses water at $1000^\circ C$ and gives '$Y$'. Compounds '$X$' and '$Y$' respectively are:

The calculated magnetic moment (in Bohr magnetons) of $Cu^{2+}$ ion is