Molten sodium chloride conducts electricity due to the presence of

The first line in the Lyman series has wavelength $\lambda$. The wavelength of the first line in the Balmer series is:

What is the native home of the wild jungle fowl?

Which one of the following gives Prussian blue colour?

Which of the following has $sp^3$ hybridisation?

$A$ thin rectangular magnet suspended freely has a period of oscillation equal to $T.$ Now it is broken into two equal halves (each having half of the original length) and one piece is made to oscillate freely in the same field. If its period of oscillation is $T',$ the ratio $T'/T$ is :-