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What percentage of U-238 radionuclides in a sample remain after 3 half-lives?  Assume 100 % initially at time zero.

There are 2.54 cm in 1 inch and 36 inches in 1 yard.  A footprint was measured to be 0.28 yards.  This measurement should be reported as  _____ centimeters. Express to correct number of significant figures.

There are 2.54 cm in 1 inch and 36 inches in 1 yard.  A footprint was measured to be 0.25 yards.  This measurement should be reported as  _____ centimeters. Express to correct number of significant figures.

If the pH of a solution is 12, what is the [H+]?

What is the mass (in grams) of 1.75 moles of NH3?

What is the %S in K2S?

Which one of the following lists contains a transition metal, an alkali metal, and a metalloid, in that order?

What nuclide is produced when Ar-39 decays by beta emission?

Balance the following equation: ___Al  +  ___H2SO4  

This question is a bonus question worth 3.5 points. Determine the [OH-] of a solution with a pH = 12.6