Atomic Structure Practice Test 5

N₂⁺ = 1s2, 2s2, 2p1
No. of unpaired electrons = 1

Explanation:-

An atomic number of Calcium $Ca$=20.

Therefore the electronic configuration of calcium is 1s2, 2s2, 2p6, 3s2, 3p6, 4s2 

The nearest noble configuration is 1s2, 2s2, 2p6, 3s2, 3p6 =18(Argon)

$Ca$=[Ar]4s2

Explanation:-

Hund's rule states that:

1. Every orbital in a sublevel is singly occupied before any orbital is doubly occupied.
2. All of the electrons in singly occupied orbitals have the same spin (to maximize total spin).

Explanation:

Explanation:-

The orbital energies are compared with the help of $n+l$ rule. The higher value of $n+l$, higher is the energy of the orbital.

$5d=n+l=7$

$5f=n+l=8$

$6s=n+l=6$

$6p=n+l=7$

The $n+l$ value is greatest for 5f orbital. 

Explanation:-

Nickel is in the 4th energy level, d block, 7th column, this means that the electron configuration will end 3d8 with the d orbital being one level lower than the energy level it is on.
Ni=1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d8
Ni=[Ar]4s2, 3d8

Explanation:-

The correct order of increasing energy of the listed orbitals in the atom of titanium is $3s<3p<4s<3d$.
The energy of 4s orbital is lower than the energy of 3d orbital.
Due to this, 4s orbital is filled first followed by 3d orbital.

Explanation:-

An atomic number of Calcium $Ca$=20.

Therefore the electronic configuration of calcium is 1s2, 2s2, 2p6, 3s2, 3p6, 4s2 

The nearest noble configuration is 1s2, 2s2, 2p6, 3s2, 3p6 =18(Argon)

$Ca$=[Ar]4s2

Explanation:-

In Order to Solve Such a MCQs Apply the Concept of ( n+ l ) Rule

$(n+1)$ values for ,$4d=4+2=6$
$5p=5+1=6$
$5f=5+3=8$
$6p=6+1=7$
$\therefore$ Correct order of energy would be $5f>6p>5p>4d$

Explanation:-

Explanation:-

If the principle quantum number n = 6, the correct sequence of filling of electron will be $ns\to (n-2)f\to (n-1)d\to$np.

Here, $n=6$. Hence, the correct sequence of filling of electron will be $6s\to 4f\to 5d\to$$6p$.

Explanation:

Explanation:-

Two electrons in same orbital have opposite spins as; +1/2 & -1/2. Therefore they can be distinguished from their spin quantum number.

Explanation:-

Explanation:-

as we know: 
for 
n=3 and l=1 
we have
3p
now p contains 3 orbitals
Px, Py and Pz 
each contain 2 electrons 
so total 6 electrons

Explanation:-

$n=3,l=1,m=1$ This implies it is an orbital of $3p$ sub shell. Any orbital can have a maximum of $2$ electrons with spin quantum number $\pm 1/2$. Thus the max. number of electrons with $n=3,l=1,m=1$ are $2$

Explanation: 

Hunds Rule of Maximum Multiplicity rule states that for a given electron configuration, the term with maximum multiplicity falls lowest in energy. According to this rule electron pairing in p, d and f orbitals cannot occur until each orbital of a given subshell contains one electron each or is singly occupied

Explanation:

Explanation:-

Explanation:

Explanation:-

Schrodinger wave equation give the information about n (principal quantum number),l (angular quantum number) and m (magnetic quantum number) but s (this is called the spin quantum number ) that describe the angular momentum of an electron is given by Wolfgang Pauli.

Explanation;-

According to the Aufbau rule the value of quantum no is related to the
n= principal quantum no.

Value of l (Azimuthal quantum no.) = n−1

Value of m ( magnetic quantum no. ) = −l to +l

Value of s (spin quantum no.) = +1/2 or −1/2

Explanation:-

As we know that  En ∝ [−1 / n² ]  where n is the number of orbit. Hence, as the value of n increases, energy of the electron also increases. Hence, when n becomes infinite, energy also becomes infinite. Hence, due to this reason maximum energy is possessed by an electron, when it is present at infinite distance from the nucleus.

Explanation:

Angular nodes = n-ℓ-1

Explanation:-

For an atom to exist in equilibrium, there should be minimum repulsion between its electron pairs. Therefore, their orbitals containing electron pairs are oriented in such a way that the repulsion between electron clouds becomes minimum.

Explanation: 

For a non-directional orbit means it is spherically symmetric which is possible only for the s orbital which has $l=0$.

Explanation:-

Aufbau rule or Principle

• The word 'Aufbau' in German means 'building up'. The building up of orbitals means the filling up of orbitals with electrons
• It states that in ground state of atom, the orbitals are filled in increasing order of their energies.
• So electrons first occupy the lowest energy orbital available to them and enter into higher energy orbitals only after the lower energy orbitals are filled as per Pauli Exclusion principle & Hund Rule
• Now we know that energy of a given orbital depends upon effective nuclear charge and different type of orbitals are affected to different extent. So there is no single ordering of energies of orbitals which will be universally correct for all atoms
• But Following ordering can be used to predict the configuration of electrons in atom
  1s, 2s ,2p, 3s ,3p ,4s ,3d ,4p, 5s,4d,5p,4f,5d,6pThis can be remembered with below diagram
  
• The above order is based on Madulung Rule which states that a.The sum of the values of the principal quantum numbers (n) and azimuthal quantum number (l) i.e (n+l) determined the energy level of an orbital.Subshell having lower n+l value will be filled first
  b.The lower value of the sum of (n+l) implies that the energy of the orbital is low. If the value of n+l for two orbitals is equal then the orbital with a lower value of n will have a lower energy level.

Explanation:  

The number of nodes is the difference of principal quantum number and one. It is given by the following formula: Number of nodes = Principal quantum number - 1

Now find the number of nodes for all the given options.
5s→Number of nodes = 5 - 1 = 45s→Number of nodes = 5 - 1 = 4
5p→Number of nodes = 5 - 1 = 45p→Number of nodes = 5 - 1 = 4
5d→Number of nodes = 5 - 1 = 45d→Number of nodes = 5 - 1 = 4
Note that the number of nodes depends on the principal quantum number. As all have the same principal quantum number, they all will have the same number of nodes too

Explanation:-

A) The electronic configuration of Cr is [Ar]3d5, 4s1 (atomic number of Cr = 24).Correct.
B) The magnetic quantum number may have a negative value.Correct.The magnetic quantum number is the third of a set of quantum numbers which describe the unique quantum state of an electron and is designated by the letter m. The magnetic quantum number denotes the energy levels available within a subshell. way of stating the formula for the magnetic quantum number is (m= -l to +l)the eigen value.
C) In silver atom 23 electrons have a spin of one type and 24 of the opposite type. (Atomic number  = 47).Correct.in every atom half the electrons are having +1/2 and the half and oine more than half are hiving -1/2.
D) The oxidation state of nitrogen in NH3​ is -3.Correct.It is -3. Each H atom has a charge or +1. So to balance this, the N atom has a net charge of -3. Thus it becomes electrically neutral. Hence options A,B,C & D are correct.