Please answer all questions.

1			What is the binding energy of an alpha particle (a 4He nucleus)? The mass of an alpha particle is 4.001 51 u.
			A)	27.86 MeV
			B)	28.33 MeV
			C)	27.95 MeV
			D)	28.29 MeV
2			The half-life of carbon-14 is 5.7 × 103 years. What fraction of a sample of 14C will remain unchanged after a period of five half-lives?
			A)	0.20
			B)	0.10
			C)	0.031
			D)	0.50
3			Cesium-124 has a half-life of 31 s. What fraction of a cesium-124 sample will remain after 0.10 h?
			A)	0.086
			B)	4.66 × 10-10
			C)	0.00032
			D)	0.17
4			The tar in an ancient tar pit has a 14C activity that is only about 4.00 percent of that found for new wood of the same density. What is the approximate age of the tar?
			A)	3.37 × 102 years
			B)	26.6 × 103 years
			C)	1.85 × 104 years
			D)	3.31 × 102 years
5			By how much does the mass of a heavy nucleus change as it emits a 4.8-MeV gamma ray?
			A)	5.2 × 10-3 u = 8.6 × 10-30 kg
			B)	4.5 × 103 u = 7.4 × 10-24 kg
			C)	1.9 × 102 u = 3.2 × 10-25 kg
			D)	9.4 u = 8.6 × 10-26 kg
6			By natural radioactivity 238U emits an a-particle. The heavy residual nucleus is called UX1. UX1 in turn emits an electron. The resultant nucleus is called UX2. Determine the atomic number and mass number for (a) UX1 and (b) UX2.
			A)	(a) 90, 234 (b) 91, 234
			B)	(a) 88, 236 (b) 89, 234
			C)	(a) 91, 237 (b) 91, 233
			D)	(a) 93, 238 (b) 88, 230
7			(a) What is the mass defect of the 1H atom due to the binding energy of the electron (in the ground state)? (b) Should we worry about this mass defect when we calculate the mass of the 1H nucleus by subtracting the mass of one electron from the mass of the 1H atom?
			A)	(a) 1.46 × 10-8 u; (b) yes
			B)	(a) 1.46 × 10-8 u; (b) no
			C)	(a) 1.52 × 10-8 u; (b) no
			D)	(a) 1.52 × 10-8 u; (b) yes
			E)	(a) 1.37 × 10-8 u; (b) no
8			Two isotopes of an element have
			A)	the same number of nucleons in their nuclei.
			B)	the same number of protons as well as neutrons.
			C)	the same number of protons but a different number of neutrons.
			D)	a different number of protons but the same number of neutrons.
9			The chemical properties of an atom (what element it is) are determined by
			A)	its atomic number.
			B)	its mass number.
			C)	its neutron number.
			D)	All of these are correct.