Nuclei-Quiz-13

NUCLEI QUIZ-13

Dear Readers,

JEE Advanced Physics Syllabus can be referred by the IIT aspirants to get a detailed list of all topics that are important in cracking the entrance examination. JEE Advanced syllabus for Physics has been designed in such a way that it offers very practical and application-based learning to further make it easier for students to understand every concept or topic by correlating it with day-to-day experiences. In comparison to the other two subjects, the syllabus of JEE Advanced for physics is developed in such a way so as to test the deep understanding and application of concepts.

Q1 An energy of 24.6 eV is required to remove one of the electrons from a neutral helium atom. The energy (in eV) required to remove both the electrons from a neutral helium atom is

•   79.0
•   51.8
•   49.2
•   38.2

Solution

Q2 If _92 U^238 changes to _85 At^210 by a series of α- and β-decays, the number of α- and β-decays undergone is

•   7 and 5
•   7 and 7
•   5 and 7
•   7 and 9

Solution

Q3 The probability of survival of a radioactive nucleus for one mean life is

•   1/e
•   1-1/e
•   ln⁡2/e
•   1-ln⁡2/e

Solution

Q4A radioactive nuclide is produced at the constant rate of n per second (say, by bombarding a target with neutrons). The expected number N of nuclei in existence t s after the number is N_0 is given by

•   N=N_0 e^(-λt)
•   N=n/λ+N_0 e^(-λt)
•   N=n/λ+(N_0-n/λ) e^(-λt)
•   N=n/λ+(N_0+n/λ) e^(-λt)

Q5. Beta rays emitted by a radioactive material are

•   Electromagnetic radiations
•   The electrons orbiting around the nucleus
•   Charged particles emitted by the nucleus
•   Neutral particles

Solution

(c)

β-particles are radioactive material emitted by the nucleus

Q6A radio isotope ‘X’ has a half-life of 10 s. Find the number of nuclei in the sample (if initially there are 1000 isotopes which are falling from rest from a height of 3000 m) when it is at a height of 1000 m from the reference plane

•   50
•   250
•   29
•   100

Solution
(b) Calculate time when it reaches a height of 1000 m, then use A=λN

Q7. Half-life of a radio active substance A is 4 days. The probability that a nucleus will decay in two half-lives is

•   1/4
•   3/4
•   1/2
•  Area

Solution
(b) After two half-lives 1/4 th fraction of nuclei will remain undecayed or 3/4 th fraction will decay. Hence , the probability that a nucleus decays in two half-lives is 3/4.

Q8 The half-life of radioactive radon is 3.8 days. The time at the end of which 1/20th of the radon sample will remain undecayed is (given log_10⁡〖e=0.4343)〗

•   3.8 days
•   16.5 days
•   33 days
•   76 days

Solution

Q9. In the case of thorium (A=232 and Z=90), we obtain an isotope of lead (A=208 and Z=82) after some radioactive disintegration. The number of α- and β-particles emitted are, respectively, span>

•   6, 3
•   6, 4
•   5, 5
•   4, 6

Solution

Q10 What would be the energy required to dissociate completely 1 g of Ca-40 into its constituent particles? Given: Mass of proton =1.007277 a.m.u., Mass of neutron =1.00866 a.m.u. Mass if Ca-40 =39.97545 a.m.u (take 1 a.m.u.=931 MeV)

• 4.813×10^24 MeV 
•   4.813×10^24 eV
• 4.813×10^23 MeV
• None of the above
  
  

Solution