How much of a radioactive parent isotope will remain after three half-lives have passed?

a. one-eighth

b. three-halves

c. one-third

d. one-sixth?

The rate constant of a reaction is 4.50*10-5 L/mol·s at 195°C and 3.20*10-3 L/mol·s at 258°C. What is the activation energy of the reaction?

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Nitrogen has two naturally occurring isotopes, N-14 and N-15. The atomic mass of nitrogen is 14.007 amu. Which isotope is more abundant in nature? Explain

How many molecules are in CO2?

Those elements with 1,2,3 electrons in their outermost shells are gases

In the synthesis reaction, the white powder produced is magnesium oxide (mgo, mm = 40.3 g/mol). how many moles of magnesium oxide were formed (number of moles = mass (g) / molar mass (g/mol)) ? choose the closest answer. a. 0.21 moles b. 0.

Which of the following is the most likeley example of an favorable mutation A. A mutation that makes a rabbit able run faster B. A mutation that changes the rabbit's fur to bright orange C. A mutation that changes the color of the rabbit's eyes D.

Which of these mole ratios is possible for this reaction? FeCl3 + 3NaOH → Fe (OH) 3 + 3NaCl 1:1 1:3 3:1 2:3

The chemical equation for reduction of phosphorite Ca3 (PO4) 2

Synthesize What environmental effects are shared by all fossil fuels?