REACTIVITY SERIES - IGCSE PRACTICE QUESTIONS
VOLUME OF PRISMS, SOLIDS , 3D SHAPES - Formulas , PROBLEMS
VOLUME OF PRISMS, SOLIDS , 3D SHAPES - Formulas , PROBLEMS
Volume of Right Triangular Prism, Rectangular Prism, Trapezoidal Prism, Cylinder, Cuboid - FORMULA, NUMERICAL, PROBLEMS
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NCERT Solutions for Class 9 Maths Chapter 13 Surface Areas and Volumes
NCERT Solutions for Class 9 Maths Chapter 13 Surface Areas and Volumes
MAHARASHTRA BOARD SOLUTIONS - CHAPTER 13 - CLASS 11 CHEMISTRY NUCLEAR CHEMISTRY AND RADIOACTIVITY
MAHARASHTRA BOARD SOLUTIONS - CHAPTER 13 - CLASS 11 CHEMISTRY NUCLEAR CHEMISTRY AND RADIOACTIVITY
Half life of 18F is 110 minutes. What
fraction of 18F sample decays in 20
minutes ?
Half life of 35S is 87.8 d. What
percentage of 35S sample remains after
180 d ?
Half life 67Ga is 78 h. How long will it
take to decay 12% of sample of Ga ?
0.5 g Sample of 201Tl decays to 0.0788 g
in 8 days. What is its half life ?
65% of 111In sample decays in 4.2 d.
What is its half life ?
A 3/4 of the original amount of
radioisotope decays in 60 minutes. What
is its half life ?
How many - particles are emitted
by 0.1 g of 226Ra in one year?
A sample of 32P initially shows activity
of one Curie. After 303 days the activity
falls to 1.5 × 10^4 dps. What is the half life
of 32P ?
Half life of radon is 3.82 d. By what time
would 99.9 % of radon will be decayed.
fraction of 18F sample decays in 20
minutes ?
Half life of 35S is 87.8 d. What
percentage of 35S sample remains after
180 d ?
Half life 67Ga is 78 h. How long will it
take to decay 12% of sample of Ga ?
0.5 g Sample of 201Tl decays to 0.0788 g
in 8 days. What is its half life ?
65% of 111In sample decays in 4.2 d.
What is its half life ?
A 3/4 of the original amount of
radioisotope decays in 60 minutes. What
is its half life ?
How many - particles are emitted
by 0.1 g of 226Ra in one year?
A sample of 32P initially shows activity
of one Curie. After 303 days the activity
falls to 1.5 × 10^4 dps. What is the half life
of 32P ?
Half life of radon is 3.82 d. By what time
would 99.9 % of radon will be decayed.
A sample of old wood shows
7.0 dps/g. If the fresh sample of tree
shows 16.0 dps/g, How old is the given
sample of wood ? Half life of 14C
5730 y.
RADIOACTIVITY - THEORY, NUMERICALS, NOTES, VIDEOS (MAHARASHTRA BOARD SOLUTIONS)
RADIOACTIVITY - THEORY, NUMERICALS, NOTES, VIDEOS
MAHARASHTRA BOARD SOLUTIONS - CHAPTER 15 - CLASS 12 PHYSICS - STRUCTURE OF ATOMS AND NUCLEI
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16. Sample of carbon obtained from any living organism has a decay rate of 15.3 decays per gram per minute. A sample of carbon obtained from very old charcoal shows a disintegration rate of 12.3 disintegrations per gram per minute. Determine the age of the old sample given the decay constant of carbon to be 3.839 x 10^-12 per second. [Ans: 1803 yrs]
17. The half-life of Sr is 28 years. Determine the disintegration rate of its 5 mg sample.
[Ans: 2.626 x10 '° s-9
[Ans: 2.626 x10 '° s-9
18. What is the amount of Co necessary to provide a radioactive source of strength 10.0 mCi, its half-life being 5.3 years? [Ans: 8.88x 10-6g]
19. Disintegration rate of a sample is 10^10 per hour at 20 hrs from the start. It reduces to 6.3 x 109 per hour after 30 hours. Calculate its half life and the initial number of radioactive atoms in the sample.
[Ans: 15 hrs, 5.45x101
[Ans: 15 hrs, 5.45x101
20. The isotope 57Co decays by electron capture to 57Fe with a half-life of 272 d. The 57Fe nucleus is produced in an excited state, and it almost instantaneously emits gamma rays.
(a) Find the mean lifetime and decay constant for "Co.
(b) If the activity of a radiation source "Co is 2.0 pCi now, how many "Co nuclei does the source contain?
(c) What will be the activity after one year? [Ans: 3.39 x 107, 2.95 x 10-8 s-1, 2.51 x 1012 nuclei, 0.789 p.Ci]
21. A source contains two species of phosphorous nuclei, 32 P (T1/2 = 14.3 d) and 33 P (T 1/2= 25.3 d). At time t = 0, 90% of the decays are from 32P.
How much time has to elapse for only 15% of the decays to be from 32P ? [Ans: 186.6 d]
22. Before the year 1900 the activity per unit mass of atmospheric carbon due to the presence of "C averaged about 0.255 Bq per gram of carbon.
(a) What fraction of carbon atoms were 14C?
(b) An archaeological specimen containing 500 mg of carbon, shows 174 decays in one hour. What is the age of the specimen, assuming that its activity per unit mass of carbon when the specimen died was equal to the average value of the air?
Half-life of 14C is 5730 years?
[Ans: Four atoms in every 3x1012 carbon atoms were '4C, 8020 years]
-------------
12. Determine the amount of 210 Po necessary to provide a source of a particles of 5 mCi strength. The halflife of polonium is 138 days.
Example 29. In an experiment, the activity of 1.2 milligrams of radioactive potassium chloride (chloride of isotope K-40) was found to be 170 s-1. Taking molar mass of to be 0.075 kg mole ', find the number of K-40 atoms in the same and hence find the half-life of K-40. Avogadros' number =6.0 1023 mole- 1.
Example 22. The half-life of radium is 1500 years. After how many years will one gram of the pure radium
(i) reduce to one centigram ?
(ii) lose one milligram ?
(ii) lose one milligram ?
Example 24. The half life of 238 U against a-decay is 1.5 x 1017 s. What is the activity of a sample of 238 U having 25 x 1020 atoms ?
Example 25. The half life of 299 U against a-decay is 4.5 x 10° years. Calculate the activity of 1 g sample of 238 U. 92
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