Which orbital in each of the following pairs is lower in energy in a many electron atom? 3s,4s

Which of the following pairs give positive Tollen’s test?

Which compound in the following pair undergoes faster S_N1 reaction ?

Which of the following contains maximum number of lone pairs of electrons on the central atom ?

List the value of n and l for the following orbitals : 4s

Solve the following pair of linear equations by the substitution method : s-t=3 , s/3+t/2=6 .

Bohr model is a system consisting of small, dense nucleus surrounded by orbiting electrons. The electrons travel is defined circular orbits around the nuclues which orbital angular moementum is an integral multiple of h/(2pi) . While rotating in allowed orbits (stationary orbits) the electron does not radiate energy. electromagnetic radiations are emitted when the electron jumps from a higher orbit (E_(ni)) to a lower orbit (E_(nf)) . The total energy of the electron in an atom is negative. It suggests that

List the value of n and l for the following orbitals : (1) 3s

On the basis of Bohr’s theory, derive an expression for binding the energy of an electron in a hydrogen atom.

Gadolinium belongs to 4f series. It’s atomic number is 64. Which of the following is the correct electronic configuration of gadolinium ?