1) An isotope of the element Thallium, Tl-206, undergoes beta decay with a half-life of 3.1 minutes. Assume you begin with 64.00 grams of the thallium isotope, what mass of the isotope will be left after 9.3 minutes have elapsed? Report your answer to 2 decimal places.

2) Assume that a 22.0 volt energy source is in a circuit that has a resistance of 5.00 ohms. Determine the power consumption in watts. Report your answer to 2 decimal places.

3) A solution has a hydroxide-ion concentration of 1.0 x 10^-10 mol per liter. What is the pH of this solution? Report your answer to 2 decimal places.

4) The number of people this planet can support is largely determined by the amount of ammonia-based fertilizer that can be produced. Without the ability to chemically manufacture ammonia, the world's population would be closer to 1/6 of its current size. Since the early twentieth century ammonia has been produced via the process shown below.

3 H₂ + N₂ 2 NH₃

How many grams of ammonia are produced when 6.00 g of H₂ react? Report your answer to 2 decimal places.

5) A 2200 kg car is moving at a speed of 40.0 m/s. Determine the stopping distance (in meters) if the brakes supply a force of 3500 newtons. 2 decimal places.

6) A 54 newton horizontal force pushes a 5.0 kg mass sitting on a horizontal surface. Additionally, the horizontal surface exerts a 30 newton frictional force on the mass. What is the acceleration of the mass? Report your answer to 2 decimal places.