An 80.0 g sample of iodine-131 was placed in a sealed vessel forty days ago. Only 2.5 g of this isotope is now left. What is its half-life?

Carbon monoxide is formed when fuels are burned: with sulfur impurities without enough oxygen at high temperatures that contain lead

What information do you need to convert between moles and mass of a substance?

Which of these elements in group 1A has the largest atomic radius?

7. Which physical property requires no tools, scales, or other equipment to determine? A. Hardness incorrect answer B. Fracture incorrect answer C. Color incorrect answer D. Cleavage incorrect answer

Use Hess's Law to calculate the heat of reaction for the following reaction: A + 3B → 3C + 2D A + 2B → C + D H = - 20 kJ B → 2C + D H = - 45 kJ Question 10 options: +25 kJ -65 kJ -25 kJ +65 kJ

Why is parts per million a useful form of measurement when discussing environmental issues?

What affects gravity

7. An element found in period 4 would have how many energy levels/shells?

At a certain temperature this reaction follows first-order kinetics with a rate constant of 0.00285 s^-1: 2Cl_2 O_5 (g) rightarrow 2Cl_2 (g) + 5O_2 (g) Suppose a vessel contains Cl_2 O_5 at a concentration of 0.640 M.

02:Matter and Change What is one difference between a mixture and a compound? A. A compound can only be separated into its components by chemical means. B. A compound consists of more than one phase. C.