Which of the properties of radioisotopes make them useful as tracers in medical or agricultural applications?
I: Their chemical behaviour is the same as non-radioactive isotope
II: They emit various types of radiation
III: The nuclear reaction is unaffected by the chemical state of the isotope
I only
I and III
I and II
All of these
A radioactive element decays by the sequence, and with half-lives, given below:
a 2ß
X ? Y ? Z
30 min 2 days
Which of the following statements about this system are correct?
After two hours, less than 10% of the initial X is left
Maximum amount of Y present at any time before 30 min is less than 50% of the initial amount of X
Atomic numbers of X and Z are same
All of the above
The most radioactive of the isotopes of an element is the one with the largest value of its:
Half-life
Neutron number
Atomic number
Decay constant
In uranium mineral, the atomic ratio Nu-238/Npb-206 is nearly equal to one. The age (in years) of the mineral is nearly (half-life period of U-238 is 4.5 x 109 years):
3.0 x 108
4.5 x 109
3.0 x 109
4.5 x 108
KA kB
A ? product, B ? product
TA TB
A and B are two radioactive elements with half-life periods TA and TB (in years) and kA(year-1) and kB (atom-1 year-1). If half-life periods are equal, disintegration rate at the start of disintegration with same concentration would be:
kATA
0.693
Both (a) and (b)
None of these
Constituents of wine are carbon, hydrogen and oxygen. Half-lives of 13C, 15O and 3H are respectively 5730 y, 124s and 12.5y. A bottle of wine was sealed about 6 years ago. To confirm its age, which of the isotopes would you choose to determine its age?
136C
158O
31H
Any of these
Consider following statements:
I. ‘Carbon-dating’ is based on the measurement of activity of 14C
II. 40 K is used to determine age of the objects upto 1 million years old
III. The uranium-lead method is based on the natural uranium-238 decay series which ends up with the production of sable lead-206.
Select correct statements:
I, II
II, III
I, III
I, II, III