Multiple Choice QuestionsAufbau principle is not satisfied by
Cr and Cl
Cu and Ag
Cr and Mg
Cu and Na
B.
Cu and Ag
The electrons presents in the different orbitals of the same subshell can exchange their positions. Each such exchange results in release of energy, called exchange energy and hence, leads to a greater stability. As the number of exchanges that can take place is maximum in the exactly half filled and completely filled arrangements, therefore, exchange energy is maximum and hence, the stability is maximum.
29Cu - 1s2, 2s2 2p6, 3s2 3p6, 4s1, 3d10
47Ag - 1s2, 2s2 2p6, 3s2 3p6, 4s2, 3d10, 4p6 5s1, 4d10
but Aufbau principle states that electrons are filled in increasing order of energy, hence 4s orbital must be filled first than 3d orbital.
In Cu and Ag both electron first enters in the orbital of lower energy, therefore they does not satisfy Aufbau principle.
The atomic weight of an element is 39. The number of neutrons in its nucleus is one more than the number of protons. The number of protons, neutrons and electrons-respectively in its atoms would be
19, 20, 19
19, 19, 20
20, 19, 19
20, 19, 20
Out of the following electronic configurations the one of a transition element, is
1s2, 2s2 2p6, 3s2 3p6 3d10, 4s2 4p6
1s2, 2s2 2p6, 3s2 3p6 3d3, 4s2
1s2, 2s2 2p6, 3s2 3p6, 4s2
1s2, 2s2 2p6, 3s2 3p6 3d10, 4s2 4p1
A covalent bond between two atoms is formed by which of the following?
Electron nuclear attraction
Electron sharing
Electron transfer
Electrostatic attraction
Hybridisation involves
addition of an electron pair
mixing up of atomic orbitals
removal of an electron pair
separation of orbitals
Which of the following compounds in liquid state does not have hydrogen bonding?
H2O
HF
NH3
C6H6
Switch
