HOMEWORK EXAM 3:
The half life of 90Sr is 29 years. What fraction of the atoms in a sample of 90Sr would remain 175 years later? Answer
Which relation is not correct?
11p = 11H = proton
0-1e = 0-1β = electron
+10e = +10β= positron
10n = neutron
As a result of beta decay, the product nucleus is
one atomic number lower than the original element.
two atomic number higher than the original element.
one atomic number higher than the original element.
two atomic number lower than the original element.
What is X for the nuclear reaction: 21284Po à 20882Pb + X Answer
Which statement is not correct for the nuclear reaction: 146C à 147N + 0-1β ? Answer
C is radioactive.
Nucleus of C is not stable.
N lies above the belt of stability of nucleus.
One neutron in the nucleus of C converts to a proton with the release of the release of particle.
If 12% of a certain radioactive isotope decays in 5.2 years, what is the half-life of this isotope? Answer
Which statement is false?
No chemical treatments can make radioactive elements harmless.
The rate of decay (disintegration) of U-238 is proportional to its sample size.
Changes in temperature or pressure cannot affect the rate of decay (disintegration) of radioactive elements.
Decay constant maintains its constancy only at the specific temperature.
How much energy is lost or gained when a mole of cobalt-60 undergoes beta decay: 6027Co --> 6028Ni + 0-1e ?
The mass of the 6027Co atom is 59.933819 amu, and that of a 6028Ni atom is 59.930788 amu. Answer
2.724x1011 J energy is released.
2.724x1011 J energy is absorbed.
2.724x108 J energy is released.
2.724x108 J energy is absorbed.
Write a balanced nuclear equation for the reaction in which oxygen-15 undergoes positron emission. Answer
158O --> 159F + 0-1n
158O --> 148O + 10e
158O --> 159F + 0-1e
158O --> 157N + 01e
What element undergoes alpha decay to form lead-208?
Which process is not a part of the purification metals?
By what kind of element can a n-type semiconductor be doped? Answer
Here, As, Antimony
By what kind of element can a p-type semiconductor be doped? Answer
Here and Al
Which process does not show the production of metal by chemical reduction? Answer
V2O5(s) + 5Ca(l) --> 2V(l) + 5CaO(s)
TiCl4(g) + 2Mg(l) --> Ti(s) + 2MgCl2(l)
CaCO3(s) --> CaO(s) + CO2(g)
Cr2O3(s) + 2Al(s) --> 2Cr(l) + Al2O3(s)
Which one of the following is the best semiconductor?
What is amalgam?
an alloy of aluminum with another metal or metals.
an alloy of mercury with another metal or metals.
an aluminium bauxite mixture
an aluminum ferromagentic metals
What is a p-type semiconductor?
A semiconductor that contains donor impurities which have excess electrons.
A semiconductor that contains acceptor impurities which have excess electrons.
A semiconductor that contains donor impurities which are electron deficient. T
A semiconductor that contains acceptor impurities which are electron deficient.
What is doping?
Enhancing the ability of a semiconductor to conduct heat by adding small amount of certain impurities to the element.
Enhancing the ability of...
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