According to de-Broglie, matter should exhibit dual behaviour, that is both particle and wave like properties.However, a cricket ball of mass 100g does not move like a wave when it is thrown by a bowler at a speed of 100km/h.Calculate the wavelength of the ball and explain why it does not show wave nature?

Why was the change in the Bohr model of atom is required, due to which important development(s), concept of movement of an electron in an orbit was replaced by the concept of probability of finding an electron in an orbital?What is the name given to the changed model of an atom?

The arrangement of orbitals on the basis of energy is based upon their (n + 1), lower is the energy. For orbitals having same values of (n + l), the orbitals with lower value of n will have lower energy.
Based upon the above information, arrange the following orbitals in the increasing order of energy.
a) 1s 2s, 3s, 2p
b) 4s, 3s, 3p, 4d
c) 5p, 4d, 5d, 4f, 6s
d) 5f, 6d, 7s, 6p

The arrangement of orbitals on the basis of energy is based upon their (n + 1), lower is the energy. For orbitals having same values of (n + l), the orbitals with lower value of n will have lower energy.
Based upon the above information, solve the questions given below.
a) Which of the following orbitals has the lowest energy?
4d, 4f, 5s, 5p
b) Which of the following orbitals has the highest energy?
5p, 5d, 5f, 6s, 6p

An element with mass number 81 contains 31.7% more neutrons as compared to protons. Assign the atomic symbol.