Chapter 23

Find the source activity of a 1.24-Ci sample of \({ }^{13} \mathrm{~N}\) (nitrogen) \(20.0 \mathrm{~min}\) after certification. Its half-life is \(10.0 \mathrm{~min}\).

Find the half-life of a radioactive sample if its decay constant is \(1.72 \times 10^{4}\) decays/s.

Find the mass in kilograms of the \({ }_{92}^{232} \mathrm{U}\) atom if its mass in atomic mass units is \(232.037131 \mathrm{u}\).

For each given isotope, find (a) its atomic mass number, (b) its atomic number, (c) its neutron number, (d) the number of protons, (c) the number of nucleons, and (f) the number of neutrons. \({ }_{6}^{12} \mathrm{C}\)

Which atom has the \(n=2\) energy level filled?

Find the energy of an electron in its ground-state energy level in a hydrogen atom.

Find the source activity of a 2.64-Ci sample of \({ }_{6}^{14} \mathrm{C}\) (carbon) \(40 \overline{0} 0\) years after certification. Its half-life is 5370 yr.

Find the half-life of a radioactive sample if its decay constant is \(8.25 \times 10^{-6}\) decay/s.

Find the mass in kilograms of the \({ }_{90}^{228} \mathrm{Th}\) atom if its mass in atomic mass units is \(228.028716 \mathrm{u} .\)

Which atom has the \(n=1\) energy level filled?

Find the energy of an electron in the \(n=3\) energy level in a hydrogen atom.

Find the source activity of a \(0.476\) -Ci sample of \({ }_{11}^{24} \mathrm{Na}\) (sodium) \(36.5 \mathrm{~h}\) after certification. Its half-life is \(14.95 \mathrm{~h}\).

Find the remaining quantity of \({ }_{55}^{124} \mathrm{Cs}\) from an original sample of \(50.0 \mathrm{~g}\) after \(4.00 \mathrm{~min}\). Its half-life is \(30.8 \mathrm{~s}\).

For each given isotope, find (a) its atomic mass number, (b) its atomic number, (c) its neutron number, (d) the number of protons, (c) the number of nucleons, and (f) the number of neutrons. $$\frac{48}{22} \mathrm{Ti}$$

Which atom is one electron short of having the \(n=2\) energy level filled? Which atom has just one electron in the \(n=3\) energy level?

Find the source activity of a 3.98-Ci sample of \({ }_{6}^{11} \mathrm{C}\) (carbon) \(10.3 \mathrm{~h}\) after certification. Its half-life is \(20.4 \mathrm{~min}\).

Find the remaining quantity of radon 222 from an original sample of \(75.0 \mathrm{~g}\) after \(10.0\) days. Its half-life is \(3.82\) days.

For each given isotope, find (a) its atomic mass number, (b) its atomic number, (c) its neutron number, (d) the number of protons, (c) the number of nucleons, and (f) the number of neutrons. $$ { }_{58}^{141} \mathrm{Ba} $$

Find the source activity of a \(10.0-\mathrm{Ci}\) sample of \({ }^{226} \mathrm{Ra}\) (radium) \(125 \mathrm{yr}\) after certification. Its half-life is \(1590 \mathrm{yr}\)

Find the percent of a sample of \({ }_{55}^{124} \mathrm{Cs}\) that will decay in the next \(10.0 \mathrm{~s}\). Its half life is \(30.8 \mathrm{~s}\).

Find the wavelength of a photon given off in a hydrogen-filled neon tube undergoing a transition from the \(n=3\) to the \(n=2\) energy level.

Find the source activity of a \(4.00-\mathrm{Ci}\) sample of \({ }_{53}^{131}\) (iodine) \(6.00 \mathrm{~h}\) after certification. Its half-life is \(8.06\) days

Find the percent of a sample of \({ }_{92}^{-38} \mathrm{U}\) that will decay in the next 975 years. Its half-life is \(4.47 \times 10^{9}\) years.

From the Periodic Table, find (a) the atomic number and (b) the atomic mass for each element. Fe (iron)

Find the source activity of a \(75.0-\mu\) Ci sample of \({ }_{84}^{214} \mathrm{Po}\) (polonium) \(5.00 \mu \mathrm{s}\) after certification. Its half- life is \(1.50 \times 10^{-4} \mathrm{~s}\).

Find the remaining quantity of uranium 238 atoms from an original sample of \(5.50 \times 10^{20}\) atoms after \(2.45\) billion years. Its half-life is \(4.50\) billion years.

From the Periodic Table, find (a) the atomic number and (b) the atomic mass for each element. \(\mathrm{Pb}\) (lead)

From the Periodic Table, find (a) the atomic number and (b) the atomic mass for each element. Cl (chlorine)

Find the percent of \(\mathrm{a}{\underline{\phantom{xx}}}_{6}^{14} \mathrm{C}\) sample that will decay in the next 3000 years. Its halflife is 5730 years.

The nucleus of a certain element contains 6 protons and 8 neutrons. Write its chemical symbol.

Find the percent of a radioactive sample of half-life \(2.35 \mathrm{~s}\) that will decay in the next second.

The nucleus of a certain element contains 92 protons and 142 neutrons. Write its chemical symbol.

Use the Periodic Table to determine the following: Which of the elements \(\mathrm{Br}\) and \(\mathrm{Ca}\) would be expected to be more acidic?

Use the Periodic Table to determine the following: Which of the elements \(\mathrm{Br}\) and \(\mathrm{Ca}\) would be expected to be a stronger base?

Which of the elements \(\mathrm{Cl}, \mathrm{Ar}, \mathrm{I}, \mathrm{Ca}\), and \(\mathrm{K}\) is inert?

Use the Periodic Table to determine the following: Which of the elements \(\mathrm{C}, \mathrm{N}, \mathrm{O}\), and \(\mathrm{Fe}\) is a metal?