In which of the following states of matter do the molecules vibrate about their mean positions?
liquids only
solids only
liquids and gasses only
solids, liquids and gases
Correct answer is B
No explanation has been provided for this answer.
A radioactive element has a decay constant of 0.077s-1. Calculate its half-life
13.0s
9.0s
5.1s
0.5s
Correct answer is B
\(t_{\frac{1}{2}} = \frac{0.693}{\lambda} = \frac{0.693}{0.077} = 9s\)
Control in nuclear reactors is effected with boron rods because rhe rods have the ability to
absorb electrons
absorb neutron
accelerate electrons
slow down neutrons
Correct answer is B
No explanation has been provided for this answer.
Nuclear fission is preffered to nuclear fusion in the generation of energy because
very high temperature are required for fusion
the raw materials for fusion are easily obtained
energy obtained from fusion is relatively small
the by-products of fusion is very dangerous
Correct answer is C
No explanation has been provided for this answer.
When a radioactive substance undergoes a beta decay, its
mass number decreases by 1
atomic number decreases by 1
mass number increases by 1
atomic number increases by 1
Correct answer is D
No explanation has been provided for this answer.