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Question :
Problems
Show all necessary calculations. Round answers to the correct number : 1409664

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**Problems**

**Show all necessary calculations. Round answers to the correct number of significant figures. Box final numerical answers.**

67. Calculate the number of moles in 2.61 grams of silicon.

68.Calculate the number of atoms in 2.61 grams of silicon.

69. Define the term mole. Explain the relationship between mole and atomic weight.

70.What is the mass in grams of 5.82 x 10^{15 }moles of Ba?

71.12.5 grams of gold contains how many gold atoms?

72.Write the nuclear equation for the alpha emission of bismuth-210.

73. Write the nuclear equation for the beta emission of iodine-131.

74.Technetium-99 is injected into a patient in order to monitor heart function. Technetium-99 is a gamma emitter with a half-life of 6 hours. A patient receives an injection of 21 mg of Technetium-99 on a Tuesday at 9:00 a.m. How much remains on Wednesday at 11:00 p.m.?

a.Calculate the number of hours and the number of half-lives that occur between 9:00 a.m. on Tuesday and 11:00 p.m. on Wednesday.

b.Determine the amount of Technetium-99 remaining on Wednesday at

11:00 p.m.

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