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The age of the earth has been estimated by scientists as 4.54 billion years (4.54 x 109 yr). If there was an imaginary unit of “Brigg” that was equal to 1,971 minutes, how old is the earth in Briggs? (you may disregard leap years in your calculation)

Which compound below has a different empirical formula than the other three?

A piece of pure aluminum foil is cut to dimensions of 5.00 cm x 8.00 cm and its mass is measured as 0.282 g.  Given the density of Al is 2.70 g /cm3, and the diameter of a single Al atom is 2.86 x 10-8 cm, how many Al atoms span the thickness of the foil?

Which of these elements is paired incorrectly with its chemical symbol?

What will happen to the pressure of a gas if the volume is increased by a factor of 4 while holding the temperature constant?

A volatile compound is one that vaporizes (goes from the liquid to gas phase) easily. Which of the following molecules is the most volatile?

For which of the following reactions is the value of ∆Hºrxn equal to ∆Hºf of the product?

What volume of NH3 gas at STP is produced by the complete reaction of 7.5 g of H2O according to the following reaction? Mg3N2 (s) + 6 H2O (l) → 3 Mg(OH)2 (aq) + 2 NH3 (g)

Aluminum consists of only one naturally-occurring isotope. What is the mass of this isotope?

Which of these lengths is the shortest?