STRUCTURE OF ATOM Quiz-13

Chemistry Aptitude Quiz

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IIT JEE exam which consists of JEE Main and JEE Advanced is one of the most important entrance exams for engineering aspirants. The exam is held for candidates who are aspiring to pursue a career in the field of engineering and technical studies. Chemistry is important because everything you do is chemistry! Even your body is made of chemicals. Chemical reactions occur when you breathe, eat, or just sit there reading. All matter is made of chemicals, so the importance of chemistry is that it's the study of everything..

Q1. The total spin and magnetic moment for the atom with atomic number 24 are:

•  ±3,√48 BM
•  ±3,√35 BM
•  ±3/2,√48 BM
•  ±3/2,√35 BM

Solution
(a)
Atomic number =24
Structure is 3d^5,4s^1,n=6
Total spin = ±1/2×6=±3
Magnetic moment = √(n(n+2))=√(6(6+2))=√48 BM

Q2.For two different disintegration half-lives are equal at equilibrium. This is only when

•  N_1=N_2
•  λ_1=λ_2
•  (T_75 )_1=(T_75 )_2
•  All of these

Solution
(d)
〖N_1 λ_1=N_2 λ〗_2at equilibrium
N_1/t_1 =N_2/t_2 t_1and t_2 are half-lives
If t_1=t_2then N_1=N_2
If λ_1=λ_2then N_1=N_2
Since, T_75=2T_50
Hence, if (T_75 )_1=(T_75 )_2
Then N_1=N_2

Q3.  Bohr’s model of atom is not in agreement with

•  Line spectra hydrogen atom
•  Pauli’s principleergs
•  Planck’s theoryergs
•  Heisenberg’s principle

Solution
Part D

Q4.   The correct ground state electronic configuration of chromium atom is

•  Line spectra hydrogen atom
•  Pauli’s principle
•  Planck’s theory
•  Heisenberg’s principleC

Solution

Part A

Q5.

•  Proton, neutron, positron
•  Neutron, positron, proton
•  Proton, positron, neutron
•  Positron, proton, neutron

Solution
 Part A opt-right

Q6. When two electrons are placed in two degenerate orbitals of the atom, the energy is lower if their spin is parallel. The statement is based upon

•  Pauli’s exclusion
•  Bohr’s rule
• Hund’s rules
•  Aufbau principle

Solution
(c)
Hund’s rule

Q7.At two stages of disintegration, disintegration constants are respectively 1×10^(-2) s^(-1) and 1×10^(-5) s^(-1).At first stage 2000 atoms are disintegrating. At second stage number of atoms disintegrating would be

•  2
•  2×10^6
•  2×10^(-6)
•  2×10^9

Solution
(b)
For disintegration
N_1 λ_1=N_2 λ_2
N_2=λ_1/λ_2 N_1=(1×10^(-2))/(1×0^(-5) )×200
=2×10^6

Q8.The correct set of quantum numbers for the unpaired electron of chlorine atom is: nIm_l

•  2 1 0
•  2 1 1
•  3 1 1
•  3 0 0

Solution
Part C

Q9.The correct set of quantum numbers for the unpaired electron of chloride atom is n l m

•  2 1 0
•  2 1 0
•  3 1 1
•  3 0 0

Solution
(c) Cl(Z=18) [Ne]3s^2 3p^5 For the last electron: n=3,l=1,m=-1,0, or+1

Q10. The energy released during the fission of 1 kg of uranium is

•  9×10^23 ergs
•  9.0×10^10 ergs
•  9.0×10^18 ergsstorm
• 9.0×10^8 ergs

Solution
(a)
E=mc^2
=m×931 MeV

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