The radius of germanium $(Ge)$ nuclide is measured to be twice the radius of ${}_4^9Be$. The number of nucleons in $Ge$ are

$A$ value of $n$ such that $\left(\frac{\sqrt{3}}{2}+\frac{i}{2}\right)^n=1$ is

For all integers $n \geq 1$, which of the following is divisible by $9$?

$(a)$ Show that for every natural number $n$ relatively prime to $10$,there exists a natural number $m$ consisting only of digits $1$ such that $n$ divides $m$.
$(b)$ Hence or otherwise,show that every positive rational number can be expressed in the form $\frac{a}{10^b(10^c-1)}$ for some natural numbers $a, b, c$.

Which of the following factors does $NOT$ favor the formation of an electrovalent (ionic) bond?

The number of moles of electrons required to deposit $36 \ g$ of $Al$ from an aqueous solution of $Al(NO_3)_3$ is (At. wt. of $Al = 27$)