Let $f$ be a non-zero real-valued continuous function satisfying $f(x+y)=f(x) \cdot f(y)$ for all $x, y \in R$. If $f(2)=9$,then $f(6)$ is equal to

During the reaction of permanganate with thiosulphate,the change in oxidation state of manganese occurs by a value of $3$. Identify which of the below media will favour the reaction.

If the length of a stretched string is shortened by $40 \%$ and the tension is increased by $44 \%$,then the ratio of the final and initial fundamental frequencies is :

$A$ person moves $30\, m$ north and then $20\, m$ towards east and finally $30\sqrt{2}\, m$ in south-west direction. The displacement of the person from the origin will be

In a potassium atom,the electronic energy levels are in the following order:

The masses of neutron,proton and deuteron in amu are $1.00893$,$1.00813$ and $2.01473$,respectively. The packing fraction of the deuteron in amu is