91Ó°ÊÓ

Why are scientists continuing to try to build a fusion reactor even though very high temperatures required have been difficult to reach and maintain?

Uranium- 238 decays in a series of nuclear changes until stable lead-206 is produced. Complete the following nuclear equations that are part of the uranium- 238 decay series: a. \({ }_{92}^{238} \mathrm{U} \longrightarrow{ }_{90}^{234} \mathrm{Th}+\) ? b. \({ }_{90}^{234} \mathrm{Th} \longrightarrow ?+{ }_{-1}^{0} e\) c. \(? \longrightarrow{ }_{86}^{222} \mathrm{Rn}+{ }_{2}^{4} \mathrm{He}\)

The iceman known as "Ötzi" was discovered in a high mountain pass on the Austrian-Italian border. Samples of his hair and bones had carbon- 14 activity that was about \(50 \%\) of that present in new hair or bone. Carbon- 14 is a beta emitter. a. How long ago did "Ötzi" live if the half-life for \(\mathrm{C}-14\) is \(5730 \mathrm{y} ?\) b. Write a balanced nuclear equation for the decay of carbon- 14 .

Complete and balance each of the following nuclear equations: a. \(\mathrm{Bi}-209+\mathrm{Cr}-54 \longrightarrow ?+{ }_{0}^{1} n\) b. Np-237 undergoes alpha decay. c. \({ }_{2}^{4} \mathrm{He}+{ }_{95}^{241} \mathrm{Am} \longrightarrow ?+2_{0}^{1} n\)

The half-life for the radioactive decay of calcium-47 is \(4.5\) days. If a sample has an activity of \(4.0 \mu \mathrm{Ci}\) after 18 days, what was the initial activity of the sample?

A \(16-\mu \mathrm{g}\) sample of sodium- 24 decays to \(2.0 \mu \mathrm{g}\) in \(45 \mathrm{~h}\). What is the half-life of sodium- 24 ?