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CBSE - XII Science - Physics - Nuclei
55Cs124(Z=55,A=124) has a half life of 30.8s. (a) If we have 7.8 microgram initially, how many nuclei are presents? How many are present 2 min later? (b) What is the activity at this time? (c) After how much time will the activity drop to less than about 1 per second?
Asked by arjunsah797
16th May 2022,
2:17 PM
CBSE - XII Science - Physics - Nuclei
how are we supposed to solve this question
Asked by merinlijo_20002
17th June 2020,
10:05 AM
CBSE - XII Science - Physics - Nuclei
Carbon-14(C14) decays at a constant rate in such a way that it reduces to 50% in 5568 years. Find the age of an old wooden piece in which the carbon is only 25% of the original.
Asked by rajubarman
1st December 2019,
10:03 AM
CBSE - XII Science - Physics - Nuclei
Radioactive nuclei
Asked by alanpeter9611
23rd February 2019,
7:47 PM
CBSE - XII Science - Physics - Nuclei
Radioactive elements
Asked by alanpeter9611
22nd February 2019,
11:24 PM
CBSE - XII Science - Physics - Nuclei
Half-life period of a radioactive sample is 2 days. If the number of nuclei initially present is
, find the number of nuclei present after 8 days?
, find the number of nuclei present after 8 days?
Asked by sd2021667
4th December 2018,
4:46 PM
CBSE - XII Science - Physics - Nuclei
figure for 13.6 in chapter nuclei
Asked by silladech
16th November 2018,
11:14 AM
CBSE - XII Science - Physics - Nuclei
Differentiate between alpha,beta and gamma decay.
Asked by pksunilnair
4th December 2017,
9:22 AM
CBSE - XII Science - Physics - Nuclei
from boards point of view is it important to learn speed of emmitted alpha particle from the topic alpha decay?
Asked by vasturushi
4th November 2017,
12:23 PM
CBSE - XII Science - Physics - Nuclei
A radioactive material of half-life T was produced in a nuclear reactor at different instants, the quantity produced second time was twice of that produced first time. If now their present activities are 
respectively then their age difference equals:
(A) 
(B) 
(C)
(D) 
respectively then their age difference equals:
Asked by yugibo
13th April 2016,
9:48 PM
CBSE - XII Science - Physics - Nuclei
There are two radionuclei A and B. A is an alpha emitter and B is a beta emitter. Their distintegration constants are in the ratio of 1 : 2. What should be the ratio of number of atoms of two at time t = 0 so that probabilities of getting 
particles are same at time t = 0.
(A) 2 : 1
(B) 1 : 2
(C) e
(D) 
particles are same at time t = 0.
Asked by yugibo
13th April 2016,
9:35 PM
CBSE - XII Science - Physics - Nuclei
The following table shows some measurements of the decay rate of a radionuclide sample .Find the disintegration constant .
Time lnR
36 5.08
100 3.29
164 1.52 218 1.00
Asked by Rajeev
16th February 2016,
9:28 PM
CBSE - XII Science - Physics - Nuclei
What is the half life period of carbon 14?
Asked by Balbir
30th September 2015,
9:15 PM
CBSE - XII Science - Physics - Nuclei
Write symbolically the nuclear β+ decay process of. Is the decayed product X an isotope or isobar of ()? Given the mass values m () = 11.011434 u and m (X) = 11.009305 u. Estimate the Q-value in this process.
Asked by Topperlearning User
10th July 2015,
8:41 AM
CBSE - XII Science - Physics - Nuclei
can a radioactive nucleus emit an alpha particle and a beta particle simultaneously?
Asked by haider.samina
7th March 2015,
10:40 AM
CBSE - XII Science - Physics - Nuclei
A given number of atoms No of radio active element with half life T is uniformly distributed in a blood stream of a :
1)normal person, A having total volumn of blood,V
2)Person B in need of blood tranfusion having volumn,V' of blood in the body.
The number of radioactive atoms per unit volumn in the blood streams of 2 persons after a time nT are found to be N1,N2. Prove mathematically that the additional volume of blood need to be tranfused in the body of B is
[(N2-N1)/N2}V.
Asked by Preethu S
23rd February 2015,
10:24 AM
CBSE - XII Science - Physics - Nuclei
why would a nucleus want to disintegrate and form a nuclei
Asked by Sourav Jha
6th February 2015,
8:07 AM
CBSE - XII Science - Physics - Nuclei
At a given instant there are 25% undecayed radioactive nuclei in a sample. After 10 sec, the number of undecayed nuclei is reduced to 12.5%.
calculate a) mean life of the nuclei b)the time in which the number of undecayed nuclei will further reduce to 6.25% of the reduced number.
Asked by Duwanie
25th November 2014,
12:20 AM
CBSE - XII Science - Physics - Nuclei
What are 
-particles? In the reaction 
give the atoms number and mass number of Y.
-particles? In the reaction give the atoms number and mass number of Y.
Asked by Topperlearning User
9th July 2014,
6:53 PM
CBSE - XII Science - Physics - Nuclei
A radioactive sample contains 2.2 mg of pure 
which has half life period of 1224 seconds. Calculate
(i) the number of atoms present initially.
(ii) the activity when 5μg of the sample will be left.
which has half life period of 1224 seconds. Calculate
Asked by Topperlearning User
9th July 2014,
6:46 PM
CBSE - XII Science - Physics - Nuclei
State radioactive decay law and hence derive the relation N = No e-λt where symbols have their usual meanings
Asked by Topperlearning User
9th July 2014,
5:10 PM
CBSE - XII Science - Physics - Nuclei
A radioactive uncleus undergoes a series of decay according to the scheme
If the mass number and atoms number of A are 180 and 72 respectively, what are there number for A4?
Asked by Topperlearning User
9th July 2014,
4:44 PM
CBSE - XII Science - Physics - Nuclei
Define decay constant of a radioactive sample. Which of the following radiation α-rays, β-rays and y-rays, (i) Are similar to x - rays? (ii) Are easily absorbed by matter?
Asked by Topperlearning User
9th July 2014,
4:26 PM
CBSE - XII Science - Physics - Nuclei
Complete the following nuclear reactions
(a) 4Be9 + 1H1 →3Li6 + ................
(b) 5B10 + 
→ 
+ ..............
→ + ..............
Asked by Topperlearning User
9th July 2014,
4:15 PM
CBSE - XII Science - Physics - Nuclei
How many α and β-partiles are emitted 90Th232 changes to 82Pb208?
Asked by Topperlearning User
9th July 2014,
4:06 PM
CBSE - XII Science - Physics - Nuclei
Calculate the amount of energy released during the decay of 
Given :
1.atomic mass of 
=238.05079u
2. atomic mass of 
= 234.04363
3.atomic mass of 
= 4.00260
lu = 931.5 MeV/c2.
Is this decay spontaneous? Give reason.
decay of =238.05079u = 234.04363 = 4.00260
Asked by Topperlearning User
9th July 2014,
3:56 PM
CBSE - XII Science - Physics - Nuclei
State the law of radioactive decay. Plot a graph showing the number (N) of undecayed nuclei as a function of time (t) for a given radioactive sample having half life T1/2. Depict in the plot the number of undecayed nuclei at (i) t = 3 T1/2 and (ii) t = 5 T1/2.
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
(i) Define 'activity' of a radioactive material and write its S.I. unit. (ii) Plot a graph showing variation of activity of a given radioactive sample with time. (iii) The sequence of stepwise decay of a radioactive nucleus is If the atomic number and mass number of D2 are 71 and 176 respectively, what are their corresponding values for D?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
The radioactive isotope D decays according to the sequence If the mass number and atomic number of are 176 and 71 respectively, what is (i) the mass number (ii) atomic number of D?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
Explain, with the help of a nuclear reaction in each of the following cases, how the neutron to proton ratio changes during (i) alpha- decay (ii) beta-decay?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
State the law of radioactive decay. Plot a graph showing the number (N) of undecayed nuclei as a function of time (t) for a given radioactive sample having half life
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
(i) Define 'activity' of a radioactive material and write its S.I. unit. (ii) Plot a graph showing variation of activity of a given radioactive sample with time. (iii) The sequence of stepwise decay of a radioactive nucleus is If the atomic number and mass number of D2 are 71 and 176 respectively, what aretheir corresponding values for D?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
The ground state energy of hydrogen atom is -13.6eV (i) What is the kinetic energy of an electron in the second excited state ? (ii) If the electron jumps to the ground state from the second excited state, calculate the wavelength of the spectral line emitted. OR
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
Define ionisation energy. What is its value for hydrogen atom?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
Give the mass number and atomic number of elements on the right hand side of the decay process.
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
Define half life of a radioactive element. Write its S.I. unit. derive expression for half life?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
A radioactive nuclide decays to form a stable nuclide its half life is 3 minutes. What fractions of its 1g will remain radioactive after 9 minutes?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
If the activity of a radioactive substance drops to 1/8 th of its initial value in 30 years, find its half life period?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
A neutron is absorbed by a 3Li nucleus with subsequent emission of alpha particle. Write the corresponding nuclear reaction?
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
What fraction of tritium will remain after 25 years? Given half life of tritium as 12.5 years.
Asked by Topperlearning User
4th June 2014,
1:23 PM
CBSE - XII Science - Physics - Nuclei
The half life period of a radioactive substance is 30 days. What is the time for ¾ th of its original mass to disintegrate?
Asked by Topperlearning User
4th June 2014,
1:23 PM
