A nuclear reactor delivers a power of $$10^9 \mathrm{~W}$$, the amount of fuel consumed by the reactor in one hour is

Energy of an electron in the second orbit of hydrogen atom is $$E_2$$. The energy of electron in the third orbit of $$\mathrm{He}^{+}$$ will be

The figure shows standing de-Broglie waves due to the revolution of electron in a certain orbit of hydrogen atom. Then, the expression for the orbit radius is (All notations have their usual meanings)

An electron in an excited state of $$\mathrm{Li}^{2+}$$ ion has angular momentum $$\frac{3 h}{2 \pi}$$. The de-Broglie wavelength of electron in this state is $$p \pi a_0$$ (where, $$a_0=$$ Bohr radius). The value of $$p$$ is