STRUCTURE OF ATOM Quiz-6

Chemistry Aptitude Quiz

Dear Readers,

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. Tritium, _1^3 Hhas a half-life of 12.26 yr. A 5.00 mL sample of tritiated water has an activity of 2.40×10^9 cpm.How many years will it take for the activity to fall to 3.00×10^8 cpm?

•  6.13
•  12.26
•  24.52
•  36.78

Solution

Q2.If a radioactive element is placed in an evacuated container, its rate of disintegration

•  Will be increased
•  Will be decreased
•  Will
•  Will remain unchanged

Solution
(d) The rate of disintegration does not depend upon environmental factors

Q3.  

•  1
•  2
•  0.5
•  20

Solution
(b) If T_75 of B→Cis 100 min, then T_50=50 min
Thus, N_A T_B=N_B T_A
N_A/N_B =T_A/T_B =100/50=2

Q4.   reactors

•  Fuel
•  Projectile
•  Moderator
•  Arrester

Solution

(c) Heavy water (D_2 O) works as a moderator to slow down the speed of neutron

Q5.The energy of an electron in the first Bohr orbit of H atom is -13.6 eV. The possible energy value(s) of the excited state(s) for electrons in Bohr orbits of hydrogen is(are)

•  -3.4 eV
•  -4.2 eV
•  -6.8 eV
•  +6.8 eV

Solution
 (a)
The energy of an electron in Bohr orbits of hydrogen atom is given by the expression
E_n=-Constant/n^2
Where n takes only integral values. For the first Bohr orbit, n=1, and it is given that
E_1=-13.6 eV. Hence E_n=-(13.6 eV)/n^2 Of the given values of energy, only -3.4 eV can be obtained by substituting n=2 in the above expression

Q6. Which one of the following does not consist of charged particles of matter?

•  α-particles
•  β-rays
• γ-rays
•  Anode rays

Solution
(c) γ-rays are neutral particles

Q7.The phenomenon radioactivity is associated with

•  Decay of nucleus
•   Fussion of nucleus
•  Emission of electrons or protons
•  Rearrangement in the extra nuclear electron

Solution
Part A

Q8.Which nuclear reaction is an example of α-emission?

•  
•  
•  
•  

Solution
Part A

Q9.The ratio of energy of photon of λ=2000 Å to that of λ=4000 Å is

•  2
•  1⁄4
•  4
•  1⁄2

Solution

Q10. Amongst the following elements (whose electronic configurations are given below), the one having the highest ionization energy is

•  [Ne]3s^2 3p^1
•  [Ne]3s^2 3p^3
•  [Ne]3s^2 3p^2
• [Ar]3d^10 4s^2 4p^3

Solution
Part B

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