A freshly prepared radio-isotope has activity \(64\) times the allowed level. If half-life is \(3\) h, then how long one must wait before using the isotope in radio-diagnosis?
1. \(24\) h
2.  \(18\) h
3.  \(12\) h
4. \(6\) h

The rate of radioactive disintegration at an instant for a radioactive sample of half-life 2.2 $\times {10}^{9}s$ $is$ ${10}^{10}$ $s^{-1}$. The number of radioactive atoms in that sample at that instant is:

1. 3.7$\times {10}^{20}$

2. 3.17$\times {10}^{17}$

3. 3.17$\times {10}^{18}$

4. 3.17$\times {10}^{19}$

Two stable isotopes of lithium \(^{6}_{3}\mathrm{Li}\) and \(^{7}_{3}\mathrm{Li}\) have respective abundances of \(7.5\%\) and \(92.5\%\). These isotopes have masses \(6.01512~\text{u}\) and \(7.01600~\text{u}\), respectively. The atomic mass of lithium is:
1. \(6.940934~\text{u}\)
2. \(6.897643~\text{u}\)
3. \(7.863052~\text{u}\)
4. \(7.167077~\text{u}\)

The three stable isotopes of neon: ${}_{10}{}^{20}Ne,<mspace\; width="1em"></mspace>{}_{10}{}^{21}Ne,<mspace\; width="1em"></mspace>and<mspace\; width="1em"></mspace>{}_{10}{}^{22}Ne$ have respective abundances of 90.51%, 0.27%, and 9.22%. The atomic masses of the three isotopes are 19.99 u, 20.99 u, and 21.99 u, respectively. The average atomic mass of neon is:

1. 20.1709 u
2. 21.7037 u
3. 20.1771 u
4. 21.0097 u

What is the binding energy (in MeV) of a nitrogen nucleus ${}_7{}^{14}N$?

$\mathrm{Given},<mspace\; width="1em"></mspace>$
${\mathrm{m}}_{\mathrm{p}}<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>1.007825<mspace\; width="1em"></mspace>\mathrm{u}$
${\mathrm{m}}_{\mathrm{n}}<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>1.008665<mspace\; width="1em"></mspace>\mathrm{u}$
$\mathrm{m}\left({}_7{}^{14}\mathrm{N}\right)<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>14.003074<mspace\; width="1em"></mspace>u$

1. 102.7 MeV.
2. 100.7 MeV.
3. 104.7 MeV.
4. 108.7 MeV.

A radioactive isotope has a half-life of T years. How long will it take the activity to reduce to 3.125% of its original value?

1. T years.
2. 4T years.
3. 3T years.
4. 5T years.

What is the amount of ${}_{27}{}^{60}Co$ necessary to provide a radioactive source of 8.0 mCi strength? The half-life of ${}_{27}{}^{60}Co$ is 5.3 years.

1. $8.109\times {10}^{-6}<mspace\; width="1em"></mspace>g$
2. $7.106\times {10}^{-6}<mspace\; width="1em"></mspace>g$ 
3. $7.105\times {10}^{-5}<mspace\; width="1em"></mspace>g$
4. $8.107\times {10}^{-5}<mspace\; width="1em"></mspace>g$

A given coin has a mass of \(3.0~\text g.\) The nuclear energy required to separate all the neutrons and protons from each other will be:
(for simplicity assume that the coin is entirely made of \({}^{63}_{29}\mathrm{Cu}\) atoms of mass \(62.92960~\text u,\) the mass of proton \(m_p=1.00783~\text u,\) and the mass of neutron \(m_n=1.00867 ~\text u\))
1. \(2.5296\times10^{12}~\text{MeV}\)
2. \(1.581\times10^{25}~\text{MeV}\)  
3. \(3.1223\times10^{20}~\text{MeV}\)
4. \(931.02\times10^{19}~\text{MeV}\)