During the borax bead test with $$\mathrm{CuSO_4}$$, a blue green colour of the bead was observed in oxidising flame due to the formation of :

Number of cyclic tripeptides formed with 2 amino acids A and B is :

The shortest wavelength of hydrogen atom in Lyman series is $$\lambda$$. The longest wavelength is Balmer series of He$$^+$$ is

Which of the given compounds can enhance the efficiency of hydrogen storage tank?