Advertisements
Advertisements
Question
Two stable isotopes of lithium `""_3^6"Li"` and `""_3^7"Li"` have respective abundances of 7.5% and 92.5%. These isotopes have masses 6.01512 u and 7.01600 u, respectively. Find the atomic mass of lithium.
Advertisements
Solution
Mass of lithium isotope `""_3^6 "Li"`, m1 = 6.01512 u
Mass of lithium isotope `""_3^7 "Li"`, m2 = 7.01600 u
Abundance of `""_3^6 "Li"`, η1 = 7.5%
Abundance of `""_3^7 "Li"`, η2 = 92.5%
The atomic mass of lithium atom is given as:
`"m" = ("m"_1η_1 + "m"_2η_2)/(η_1 + η_2)`
= `(6.01512 xx 7.5 + 7.01600 xx 92.5)/(92.5 + 7.5)`
= 6.940934 u
RELATED QUESTIONS
In the study of Geiger-Marsdon experiment on scattering of α particles by a thin foil of gold, draw the trajectory of α-particles in the coulomb field of target nucleus. Explain briefly how one gets the information on the size of the nucleus from this study.
From the relation R = R0 A1/3, where R0 is constant and A is the mass number of the nucleus, show that nuclear matter density is independent of A
In a periodic table the average atomic mass of magnesium is given as 24.312 u. The average value is based on their relative natural abundance on earth. The three isotopes and their masses are `""_12^24Mg` (23.98504u), `""_12^25 Mg` (24.98584u) and `""_12^26Mg` (25.98259u). The natural abundance of `""_12^24 Mg` is 78.99% by mass. Calculate the abundances of other two isotopes.
Write one balanced equation to show Emission of `beta^-` (i.e. a negative beta particle)
The mass number of a nucleus is
What is a neutrino?
The nuclei of isotopes of a given element contain the same number of ______.
All nuclides with same mass number A are called ______.
A vessel contains oil (density 0.8 g/cm3) over mercury (density 13.6 g/cm3). A sphere of homogeneous composition floats with half its volume immersed in mercury and the other half in oil. The density of the material of the sphere in g/cm3 is ______.
The valance electrons in alkali metal is a:-
Are the nucleons fundamental particles, or do they consist of still smaller parts? One way to find out is to probe a nucleon just as Rutherford probed an atom. What should be the kinetic energy of an electron for it to be able to probe a nucleon? Assume the diameter of a nucleon to be approximately 10–15 m.
A nuclide 1 is said to be the mirror isobar of nuclide 2 if Z1 = N2 and Z2 = N1. (a) What nuclide is a mirror isobar of 1123 Na? (b) Which nuclide out of the two mirror isobars have greater binding energy and why?
Deuteron is a bound state of a neutron and a proton with a binding energy B = 2.2 MeV. A γ-ray of energy E is aimed at a deuteron nucleus to try to break it into a (neutron + proton) such that the n and p move in the direction of the incident γ-ray. If E = B, show that this cannot happen. Hence calculate how much bigger than B must E be for such a process to happen.
Two nuclei may have the same radius, even though they contain different numbers of protons and neutrons. Explain.
Which of the following are the constituents of the nucleus?
What is ‘Pair production’?
A nucleus with mass number 240 breaks into two fragments each of mass number 120, the binding energy per nucleon of unfragmented nuclei is 7.6 MeV while that of fragments is 8.5 MeV. The total gain in the binding energy in the process is:
The volume occupied by an atom is greater than the volume of the nucleus by a factor of about:
The density of nuclear matter is:
Energy equivalent of 1 amu is:
