NTSE Chemistry Atomic Structure and Nuclear Chemistry MCQs Set A

Question: The mass of proton is same as that of :

• a) Carbon atom
• b) An electron
• c) Hydrogen ion
• d) Oxygen atom

Answer: Hydrogen ion

Question: The ratio of the mass of the proton to the mass of the electron is nearly -

• a) 2000
• b) 4801
• c) 1840
• d) 8140

Answer: 1840

Question: Present unit of atomic mass is -

• a) Weight of proton
• b) Weight of one neutron
• c) Weight of one hydrogen atom
• d) 1/12 th of the weight of C-12 atom.

Answer: 1/12 th of the weight of C-12 atom.

Question: An element has atomic weight W and atomic number N. The number of protons in the nucleus of its atom is:

• a) W - N
• b) W
• c) N
• d) W + N

Answer: N

Question: The increasing order of the value of e/m (charge/mass) of an electron (e), proton (p), neutron (n) and alpha particle is -

• a) e,p,n,α 
• b) n,p,e,α
• c) n,p,α,e
• d) n, ^α,p,e

Answer: n, ^α,p,e

Question:

• a) Isotopes
• b) Isobars
• c) Isomorphs
• d) Isotones

Answer: Isotones

Question: When alpha particles are sent through a gold foil most of them go straight through the foil. The reason is :

• a) Alpha particles are much heavier than the electrons
• b) Alpha particles are positively charged.
• c) Most part of the atom is empty.
• d) None of the above.

Answer: Most part of the atom is empty.

Question: Rutherford scattering experiment is related to the size of the -

• a) Nucleons
• b) Electron
• c) Atom
• d) Nucleus

Answer: Nucleus

Question: The maximum number of orbital in L - shell is -

• a) 1
• b) 4
• c) 3
• d) 6

Answer: 4

Question: Maximum number of orbital in N - shell is -

• a) 4
• b) 9
• c) 16
• d) 25

Answer: 16

More Questions.......................

Question: Which of the following has zero electron affinity ?

• a) Radon
• b) Nitrogen
• c) Oxygen
• d) Radium

Answer: Radon

Question: The isoelectronic species are -

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: An atom of an elements has 15 electrons in M shell and 2 electrons in N shell. Atomic number of the element will be:

• a) 2
• b) 15
• c) 17
• d) 27

Answer: 27

Question: If the electronic configuration of elements ‘A’ and ‘B’ are 1s2, 2s2, 2p6, 3s1 and 1s2, 2s2, 2p6, 3s2 3p4 respectively, then the formula of the compound formed by the combination of these elements will be-

• a) AB
• b) AB3    
• c) AB2      
• d) A2B

Answer: A2B

Question: Which of the following sets of orbital is arrange din the correct order of increasing energy ?

• a) 3d < 4s < 4p < 6s < 4d
• b) 2s < 3d < 4p < 4f < 1s
• c) 4s < 3d < 4p < 5s < 4d
• d) 1s < 2s < 2p < 4d < 3f

Answer: 4s < 3d < 4p < 5s < 4d

Question: Element ‘A’ with general outer shell configuration ns2 np5 usually exists as-

• a) A and forms A^- ion. 
• b) A and forms A⁺ ion.
• c) A2 and forms A^- ion.    
• d) A2 and forms A^-2 ion.

Answer: A2 and forms A^- ion.    

Question: Atoms having different atomic number and same mass number are known as-

• a) Stones
• b) Isotopes
• c) Isobars
• d) Isomorphs

Answer: Isobars

Question: The particle with the least atomic mass is-

• a) proton
• b) neutron
• c) β particle  
• d) α particle  

Answer: β particle  

Question: The time taken for 80g of uranium (t_1/2= 4.5 × 109 years) to decay to 10 g would be -

• a) 4.5 × 109 years 
• b) 9.0 × 109 years     
• c) 13.5 × 109 years
• d) 18.0 × 109 years

Answer: 13.5 × 109 years

Question: If ₉₂X²³⁸ liberates an  α- particle then the number of neutrons present in daughter nuclei is -     

• a) 144
• b) 146
• c) 92
• d) 143

Answer: 144

Question: In radioactive decay the number of α and β particles emitted respectively are -

• a) 0, 2
• b) 2, 0
• c) 1, 2
• d) 2, 1

Answer: 0, 2

Question: Consider the nuclear change,   Which of the following statements is not correct ?      

• a) age of deadwood.
• b) age of the sun.
• c) half-life of a radioactive element.
• d) amount of carbon in a substance

Answer: half-life of a radioactive element.

Question: In the study of plant respiration which of the following carbon is CO2 is used - 

• a) C - 12
• b) C - 13
• c) C - 14
• d) C - 15

Answer: C - 12

Question: Which of the following statements is wrong ?

• a) P-33 is used in the treatment of Leukemia.
• b) I-131 is used in the treatment of Thyroid Gland disorder.
• c) Co-59 can’t be used for treatment of cancer.
• d) Excessive used of radioactive elements is responsible for cancerous growth

Answer: Excessive used of radioactive elements is responsible for cancerous growth

Question: The ratio of e/m for a cathode ray :

• a) varies with a gas in a discharge tube.
• b) is fixed.
• c) varies with different electrodes.
• d) is maximum if hydrogen is taken.

Answer: varies with a gas in a discharge tube.

Question: Atoms may be regarded as comprising of protons, neutrons and electrons. If the mass attributed by electrons was doubled and the attributed by neutrons was halved, the atomic mass of ¹²C would be -      

• a) approximately the same.
• b) doubled.
• c) reduced approximately 25%.
• d) approximately halved.

Answer: doubled.

Question: The size of a nucleus is measured in-

• a) amu
• b) Angstrom
• c) cm
• d) Fermi

Answer: cm

Question: The highest value of e/m of anode rays has been observed when the discharge tube is filled with -

• a) Nitrogen
• b) Oxygen
• c) Hydrogen
• d) Helium

Answer: Helium

Question: The number of neutrons in dipositive zinc ion (Zn²⁺ with mass number 70) is-                            

• a) 34
• b) 36
• c) 38
• d) 40

Answer: 38

Question: Isotopes are identified by-
a) Positive ray analysis.
b) Aston’s mass spectrograph
c) Dempster’s mass spectrograph.
d) All the above
Answer: D

Question. Nucleons are:
a. Protons and electrons
b. Protons and neutrons
c. Electrons and neutrons
d. Electrons, protons and neutrons
Answer : B

Question. ₆C¹⁴ is formed from ₇N¹⁴ in the upper atmosphere by the action of the fundamental particle:
a. Positron
b. Neutron
c. Electron
d. Proton
Answer : B

Question. A particle having the same charge and 200 times greater mass than that of electron is:
a. Positron
b. Proton
c. Neutrino
d. Meson
Answer : D

Question. The positron is discovered by:
a. Pauling
b. Anderson
c. Yukawa
d. Segar
Answer : B

Question. Which of the following does not contain number of neutrons equal to that of ⁴⁰₁₈Ar ?
a. ⁴¹₁₉K
b. ⁴³₂₁Sc
c. ⁴⁰₂₁Sc
d. ⁴²₂₀Ca
Answer : C

Question. α-particles can be detected using:
a. Thin aluminum sheet
b. Barium sulphate
c. Zinc sulphide screen
d. Gold foil
Answer : C

Question. Which is the correct statement?
a. Isotopes are always radioactive
b. β -rays are always negatively charged particles
c. α -rays are always negatively charged particles
d. γ -rays can be deflected in magnetic field
Answer : B

Question. Which statement is incorrect?
a. α -rays have more penetrating power than β -rays
b. α -rays have less penetrating power than γ -rays
c. β -rays have less penetrating power than γ -rays
d. β -rays have more penetrating power than α -rays
Answer : A

Question. The velocity of α -rays is approximately:
a. Equal to that of the velocity of light
b. 1/10 of the velocity of light
c. 10 times more than the velocity of light
d. Un-comparable to the velocity of light
Answer : B

Question. Radioactivity was discovered by:
a. Henry Becquerel
b. Rutherford
c. J. J. Thomson
d. Madam Curie
Answer : A

Question. α -rays have:
a. Positive charge
b. Negative charge
c. No charge
d. Sometimes positive charge and sometimes negative charge
Answer : A

Question. The half-life period of a radioactive substance is 8 years.
After 16 years, the mass of the substance will reduce from starting 16.0g to:
a. 8.0g
b. 6.0 g
c. 4.0 g
d. 2.0 g
Answer : C

Question. The atomic mass of an element is 12.00710 amu. If there are 6 neutrons in the nucleus of the atom of the element, the binding energy per nucleon of the nucleus will be:
a. 7.64 MeV
b. 76.4 MeV
c. 764 MeV
d. 0.764 MeV
Answer : A

Question. The ₈₈Ra²²⁶ is:
a. n-mesons
b. u-mesons
c. Radioactive
d. Non-radioactive
Answer : C

Question. The charge on gamma rays is:
a. Zero
b. +1
c. –1
d. +2
Answer : A

Question. 1.0g of a radioactive isotope was found to reduce to 125 mg after 24 hours. The half-life of the isotope is:
a. 8 hours
b. 24 hours
c. 6 hours
d. 4 hours
Answer : A

Question. A freshly prepared radioactive source of half-life 2 hours emits radiations of intensity which is 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this source is?
a. 6 hours
b. 12 hours
c. 24 hours
d. 128 hours
Answer : B

Question. Which of the following nuclides has the magic number of both protons and neutrons?
a. ₅₀Sn¹¹⁵
b. ₈₂Pb²⁰⁶
c. ₈₂Pb²⁰⁸
d. ₅₀Sn¹¹⁸
Answer : C

Question. Positron has nearly the same weight as that of:
a. α -particle
b. Proton
c. Neutron
d. Electron
Answer : D

Question. Hydrogen and deuterium differ in:
a. Reactivity with oxygen
b. Reactivity with chlorine
c. Melting point
d. Reducing action
Answer : C

Question. In the sequence of following nuclear reactions

The value of n will be:
a. 3
b. 4
c. 5
d. 6
Answer : B

Question.

In the above sequence of reaction, the elements which are isotopes of each other are?
a. X and W
b. Y and Z
c. X and Z
d. None of these
Answer : A

Question. The nucleus of an atom is made up of X protons and Y neutrons. For the most stable and abundant nuclei
a. X and Y are both even
b. X and Y are both odd
c. X is even and Y is odd
d. X is odd and Y is even
Answer : A

Question. How many neutrons are present in the nucleus of Ra ?
a. 88
b. 226
c. 140
d. 138
Answer : D

Question. What is the value of decay constant of a compound having half-life time T_{1/ 2} = 2.95 days?
a. 2.7 x 10^-5 s⁻¹
b. 2.7 x 10⁶ s⁻¹
c. 2.7 x 10^-6 s⁻¹
d. 3 x 10⁵ s⁻¹
Answer : C

Question. What is the half-life of a radioactive substance if 75% of a given amount of the substance disintegrates in 30 minutes?
a. 7.5 minutes
b. 25 minutes
c. 20 minutes
d. 15 minutes
Answer : D

Question. A radioactive isotope decays at such a rate that after 96 minutes only 1/8^th of the original amount remains. The half-life of this nuclide in minutes is:
a. 12
b. 24
c. 32
d. 48
Answer : C

Question. The half-life of ₉₂U²³⁸ is 4.5×10⁹ years. After how many years, the amount of ₉₂U²³⁸ will be reduced to half of its present amount?
a. 9.0 × 10⁹ years
b. 13.5 × 10⁹ years
c. 4.5 × 10⁹ years
d. 4.5 × 10^4.5 years
Answer : C

Question. A radioactive isotope decays at such a rate that after 192 minutes only 1 /16 of the original amount remains. The half-life of the radioactive isotope is:
a. 32 min
b. 48 min
c. 12 min
d. 24 min
Answer : B

Question. Two Cu⁶⁴ nuclei touch each other. The electrostatics repulsive energy of the system will be:
a. 0.788 MeV
b. 7.88 MeV
c. 126.15 MeV
d. 788 MeV
Answer : C

Question. When ₉₂U²³⁵ undergoes fission. 0.1% of its original mass is changed into energy. How much energy is released if 1kg of ₉₂U²³⁵ undergoes fission?
a. 9 ×10¹⁰ J
b. 9 ×10¹¹ J
c. 9 ×10¹² J
d. 9 ×10¹³ J
Answer : D

Question. A radioactive substance takes 20 min to decay 25%. How much time will be taken to decay 75%?
a. 96.4 min
b. 68 min
c. 964 min
d. 680 min
Answer : A

Question. A heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio 8 : 1. The ratio of radii of the fragments is?
a. 1 : 2
b. 1 : 4
c. 4 : 1
d. 2 : 1
Answer : A

Question. The ratio of radii of nuclei ²⁷₁₃Al and ¹²⁵₅₂Te is approximately:
a. 6 : 10
b. 13 : 52
c. 40 : 177
d. 14 : 7
Answer : A

Question. If Avogadro’s number is 6×10²³ then the number of protons, neutrons and electrons in 14g of ₆C¹⁴ are respectively:
a. 36 × 10²³ , 48 × 10²³ , 36 × 10²³
b. 36 × 10²³ , 36 × 10²³ , 36 × 10²¹
c. 48 × 10²³ , 36 × 10²³ , 48 × 10²¹
d. 48 × 10²³ , 48 × 10²³ , 36 × 10²¹
Answer : A

Question. The binding energy per nucleon of O¹⁶ is 7.97 MeV and that of O¹⁷ is 7.75 MeV. The energy (in MeV) required removing a neutron from O¹⁷ is:
a. 3.52
b. 3.64
c. 4.23
d. 7.86
Answer : C

Question. 10 gm of a radioactive substance is reduced to 1.25 gm after 15 days. Its 1 kg mass will reduce (in how many days) to 500 gm in?
a. 500 days
b. 125 days
c. 25 days
d. 5 days
Answer : D

Question. A radioactive isotope having a half-life of 3 days was received after 12 days. It was found that there were 3 gm of the isotope in the container. The initial weight of the isotope when packed was:
a. 12 gm
b. 24 gm
c. 36 gm
d. 48 gm
Answer : D

Question. A radioactive isotope has a half-life of 10 days. If today 125 mg is left over, what was its original weight 40 days earlier?
a. 2g
b. 600 mg
c. 1 g
d. 1.5 g
Answer : A

Question. Half-life of a radioactive substance which disintegrates by 75 % in 60 minutes, will be?
a. 120 min
b. 30 min
c. 45 min
d. 20 min
Answer : B

Question. The decay constant of Ra²²⁶ is 1.37 x 10⁻¹¹ sec . A sample of Ra²²⁶ having an activity of 1.5 mill curie will contain...... atoms:
a. 4.1×10¹⁸
b. 3.7 ×10¹⁷
c. 2.05×10¹⁵
d. 4.7×10¹⁰
Answer : A

Question. 8 gm 0f the radioactive isotope, cesium-137 were collected on February 1 and kept in a sealed tube. On July 1, it was found that only 0.25 gm of it remained. So the half-life period of the isotope is:
a. 37.5 days
b. 30 days
c. 25 days
d. 50 days
Answer : B

Question. A gamma ray photon creates an electron-positron pair. If the rest mass energy of an electron is 0.5 MeV and the total kinetic energy of the electron-positron pair is 0.78 MeV, then the energy of the gamma ray photon must be:
a. 0.78 MeV
b. 1.78 MeV
c. 1.28 MeV
d. 0.28 MeV
Answer : B

Question. Binding energy per nucleon vs mass number curve for nuclei is shown in the figure. W, X, Y and Z are four nuclei indicated on the curve. The process that would release energy is:
a. Y → 2Z
b. W → X + Z
c. W → 2Y
d. X → Y + Z
Answer : C

Question. A radioactive substance decays to 1/16^th of its initial activity in 40 days. The half-life of the radioactive substance expressed in days is:
a. 2.5
b. 5
c. 10
d. 20
Answer : C

Question. A nucleus with mass number 220 initially at rest emits an α-particle. If the Q value of the reaction is 5.5 MeV.
Calculate the kinetic energy of the α-particle:
a. 4.4 MeV
b. 5.4 MeV
c. 5.6 MeV
d. 6.5 MeV
Answer : B

Question. Let p m be the mass of a proton, n m the mass of a neutron, M₁ the mass of a ²⁰₁₀Ne nucleus and M₂ the mass of a ⁴⁰₂₀Ca nucleus. Then:
a. M₂ = 2M₁
b. M₂ > 2M₁
c. M₂ < 2M₁
d. M₁ < 10(m_n + m_p)
Answer : C, D

Question. A sample of radioactive element has a mass of 10 gm at an instant t = 0. The approximate mass of this element in the sample after two mean lives is:
a. 2.50 gm
b. 3.70 gm
c. 6.30 gm
d. 1.35 gm
Answer : D

Question. Elements having different nuclear charge but the same mass number are called:
a. Isotopes
b. Isobars
c. Isomers
d. Isotones
Answer : B

Question. Emission of β -particle by an atom of an element results in the formation of its:
a. Isotope
b. Isomer
c. Isomorph
d. Isobar
Answer : D

Question. The half-life of ²¹⁵At is 100 μs. The time taken for the radioactivity of a sample of ²¹⁵At to decay to 1/16^th of its initial value is:
a. 400 μs
b. 6.3 μs
c. 40 μs
d. 300 μs
Answer : A

Question. The mean lives of a radioactive substance for α and β emissions are 1620 years and 405 years respectively. After how much time will the activity be reduced to one fourth?
a. 405 year
b. 1620 year
c. 449 year
d. None of these
Answer : C

Question. Tritium is an isotope of:
a. Hydrogen
b. Titanium
c. Tantalum
d. Tellurium
Answer : A

Question. 1 g of hydrogen is converted into 0.993 g of helium in a thermonuclear reaction. The energy released is:
a. 63 ×10⁷ J
b. 63 ×10¹⁰ J
c. 63 ×10¹⁴ J
d. 63 ×10²⁰ J
Answer : B

Question. The binding energy per nucleon of deuteron (²₁H) and helium nucleus (⁴₂He) is 1.1 MeV and 7MeV respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is:
a. 13.9 MeV
b. 26.9 MeV
c. 23.6 MeV
d. 19.2 MeV
Answer : C

Question. The masses of neutron and proton are 1.0087 amu and 1.0073 amu respectively. If the neutrons and protons combine to form a helium nucleus (alpha particles) of mass 4.0015 amu. The binding energy of the helium nucleus will be: [1 amu= 931 MeV]
a. 28.4 MeV
b. 20.8 MeV
c. 27.3 MeV
d. 14.2 MeV
Answer : A

Question. A atomic power reactor furnace can deliver 300 MW. The energy released due to fission of each of uranium atom U²³⁸ is 170 MeV. The number of uranium atoms fissioned per hour will be:
a. 5 × 10¹⁵
b. 10 × 10²⁰
c. 40 × 10²¹
d. 30 × 10²⁵
Answer : C

Question. In the nuclear fusion reaction ²₁H + ³₁H → He + n, given that the repulsive potential energy between the two nuclei is 14 7.7 10 J, − × − the temperature at which the gases must be heated to initiate the reaction is nearly?
[Boltzmann’s constant k = 1.38 x 10⁻²³ J/K]
a. 10⁹ K
b. 10⁷ K
c. 10⁵ K
d. 10³ K
Answer : A

Question. Which of the following is an isobaric pair?
a. ₆C¹³ , ₇N¹³
b. ₆C¹³ , ₇N¹⁴
c. ₇N¹⁴ , ₈O¹⁵
d. ₇N¹³ , ₈O¹⁵
Answer : A

Question. Which one of the following pairs represents isobars?
a. ³₂He and ⁴₂He
b. ²⁴₁₂Mg and ²⁵₁₂Mg
c. ⁴⁰₁₉K and ⁴⁰₂₀Ca
d. ³⁹₁₉K and ⁴⁰₁₉K
Answer : C