Structure of At...

According to Bohr's atomic theory, which of the following is correct?

What atomic number of an element $$X$$ would have to become so that the $$4th$$ orbit around $$X$$ would fit inside the $$1st$$ Bohr orbit of $$H-$$atom?

What is the seperation energy (in eV) for $$Be^{3+}$$ in the first excited state in eV?

For Hydrogen atom the ratio of time required to complete $$1$$ revolution of electron in $$I^{st},II^{nd}$$ and $$III^{rd}$$ orbit respectively is:

The sulphate of a metal $$M$$ contains $$9.87\%$$ of $$M$$. This sulphate is isomorphous with $$ZnSO_{4}.7H_{2}O$$. The atomic weight of $$M$$ is:

Which of the following frequencies is associated with the visible region of a spectrum?

The percentage of an element $$M$$ is $$53$$ percentage in its oxide of molecular formula $${ M }_{ 2 }{ O }_{ 3 }$$. Its atomic mass is about: 

Atomic number of the central atom in $${ MCl }_{ 2 }$$ is $$50$$. The shape of gaseous $${ MCl }_{ 2 }$$ is given as: 

The ratio of the radius of $$1st$$ orbit of $$H$$ atom to that of its $$4$$th excited state is:

The atomic masses of two elements A and B are 20 and 40 respectively. If x gm of A contains Y atoms, how many atoms are present in 2x gm of B?