chemistry : class12 Synthetic Origin of Livermorium : Occurrence of Group 16 elements : p-Block Elements MCQ Questions and Answers
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Synthetic Origin of Livermorium
MCQ questions and answers.
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MCQ Questions
1. Livermorium was first synthesized by bombarding which target-projectile pair in a heavy-ion fusion reaction?
A.
Curium-248 target with calcium-48 projectile
B.
Plutonium-244 target with oxygen-18 projectile
C.
Californium-249 target with carbon-12 projectile
D.
Uranium-238 target with neon-22 projectile
Correct Answer:
Curium-248 target with calcium-48 projectile
Explanation:
The first confirmed synthesis of livermorium used a calcium-48 beam directed at a curium-248 target, producing a compound nucleus with atomic number 116.
2. What compound nucleus is initially formed when calcium-48 is fused with curium-248 in the synthesis of livermorium?
A.
Livermorium-296
B.
Livermorium-292
C.
Flerovium-296
D.
Polonium-296
Correct Answer:
Livermorium-296
Explanation:
The mass numbers add as 48 + 248 = 296, while the atomic numbers add as 20 + 96 = 116. Thus, the initial compound nucleus is the excited nucleus with mass number 296 and atomic number 116.
3. Which nuclear reaction best represents the principal channel used to produce livermorium-292 from curium-248 and calcium-48?
A.
248Cm + 48Ca → 292Lv + 4n
B.
248Cm + 48Ca → 292Lv + 4p
C.
248Cm + 48Ca → 292Lv + 1α
D.
248Cm + 48Ca → 292Lv + 2n + 2p
Correct Answer:
248Cm + 48Ca → 292Lv + 4n
Explanation:
Fusion gives the compound nucleus with mass number 296 and atomic number 116. Emission of four neutrons reduces the mass number to 292 without changing the atomic number, yielding livermorium-292.
4. Why does neutron evaporation after fusion preserve the identity of the newly formed element as livermorium?
A.
Neutron emission decreases mass number but leaves atomic number unchanged
B.
Neutron emission increases atomic number by one for each emitted neutron
C.
Neutron emission converts the target nucleus into a different group-16 element
D.
Neutron emission changes atomic number while keeping mass number constant
Correct Answer:
Neutron emission decreases mass number but leaves atomic number unchanged
Explanation:
A neutron has zero charge, so its emission lowers the mass number only. The atomic number remains 116, which is the defining atomic number of livermorium.
5. The atomic number of livermorium is obtained directly by adding the atomic numbers of which fusion partners?
A.
Calcium-48 and curium-248
B.
Calcium-48 and uranium-238
C.
Oxygen-18 and curium-248
D.
Carbon-12 and californium-249
Correct Answer:
Calcium-48 and curium-248
Explanation:
Calcium contributes atomic number 20 and curium contributes atomic number 96. Their complete fusion gives atomic number 116, identifying the product as livermorium.
6. A livermorium isotope formed through the 4-neutron evaporation channel has mass number 292. What mass number must the compound nucleus have had immediately before neutron evaporation?
A.
288
B.
292
C.
296
D.
300
Correct Answer:
296
Explanation:
Four emitted neutrons account for a mass-number loss of four units. Therefore, the compound nucleus must have had mass number 292 + 4 = 296.
7. Which institution pair is most closely associated with the successful collaborative synthesis of livermorium using calcium-48 and curium-248?
A.
Joint Institute for Nuclear Research and Lawrence Livermore National Laboratory
B.
CERN and Indian Institute of Technology Delhi
C.
Oak Ridge National Laboratory and European Space Agency
D.
Los Alamos National Laboratory and University of Tokyo
Correct Answer:
Joint Institute for Nuclear Research and Lawrence Livermore National Laboratory
Explanation:
The synthesis was achieved through collaboration between the Joint Institute for Nuclear Research in Dubna and Lawrence Livermore National Laboratory in the United States.
8. In the synthesis reaction 248Cm + 48Ca → 292Lv + 4n, which conservation check confirms that the product is an isotope of element 116?
A.
Mass number changes from 296 to 292, while atomic number remains 116
B.
Mass number remains 296, while atomic number decreases to 112
C.
Atomic number increases to 120, while mass number becomes 292
D.
Both mass number and atomic number decrease by four units
Correct Answer:
Mass number changes from 296 to 292, while atomic number remains 116
Explanation:
The four neutrons remove four mass units but no protons. Consequently, the final nucleus retains atomic number 116 and is therefore livermorium-292.
9. Which observation provided the essential evidence that the short-lived nuclei produced in the experiment belonged to livermorium rather than merely to an excited compound nucleus?
A.
A correlated alpha-decay chain leading through successively lower atomic-number nuclei
B.
Immediate emission of visible light from the target material
C.
Formation of a stable bulk sample that could be weighed
D.
Conversion of all calcium projectiles into free electrons
Correct Answer:
A correlated alpha-decay chain leading through successively lower atomic-number nuclei
Explanation:
Livermorium was identified through its characteristic decay chains. Each alpha decay lowers atomic number by two and mass number by four, allowing the parent nucleus to be linked to known daughter nuclei.
10. If a livermorium-292 nucleus undergoes two successive alpha decays, what nucleus is expected after these decays, assuming no other decay occurs?
A.
Flerovium-288
B.
Copernicium-284
C.
Nihonium-284
D.
Oganesson-288
Correct Answer:
Copernicium-284
Explanation:
Each alpha decay decreases the atomic number by 2 and the mass number by 4. Starting from Lv-292 (Z = 116), two alpha decays give Z = 112 and A = 284, corresponding to copernicium-284.
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