1. If you have 25% radioactive parent atoms in a mineral crystal, and 75% daughter atoms, how many half-lives have passed?

When 1 mol of a fuel burns at constant pressure, it exchanges-3452 kJ of heat and does-11 kJ of workon the surroundings. What are ΔUand ΔH for the combustion of thisfuel?

How many moles of carbon monoxide gas (CO) would occupy 17.24 L at STP?

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For each reaction, identify the element that gets reduced and the element that gets oxidized. 2 AgCl + Zn ⟶ 2 Ag + ZnCl 2 2AgCl+Zn⟶2Ag+ZnCl2 Identify the element that gets reduced. chlorine silver zinc Identify the element that gets oxidized.

Select all of the following reactions that are endothermic. -H2 (g) + ½O2 (g) → H2O (g), ΔH = - 57.83 kcal/mole -½N2 (g) + ½O2 (g) → NO (g), ΔH = + 21.6 kcal/mole -½N2 (g) + O2 (g) + 8.1 kcal → NO2 (g) -½N2 (g) + 3/2H2 (g) → NH3 (g) + 11.

Which compound conducts electricity only in the molten state? A. sodium bromide B. calcium hydroxide C. barium sulfate D. magnesium sulfate

What is going to happen to a balloon filled with helium that is left in a car over night when the temperature drops approximately 20 degrees

Members of which group easily lose an electron to form a 1 cation? A. halogens B. alkaline earth metals C. noble gases D. alkali metals

How to convert 0.000984 into scientific notation?

What is the total pressure in a 6.00-l flask which contains 0.127 mol of h2 (g) and 0.288 mol of n2 (g) at 20.0°c?