A particular radioactive isotope has a half-life of (2.50+a) hours. if you have (24.5+b) g of the isotope at 10:00 am, how much will you have at 7:30pm? give your answer in grams (g) and with 3 significant figures.

A balloon contains 2.0 L of air at 101.5 kPa. You squeeze the balloon to a volume of. 75 L. What is the pressure of air on the inside of the balloon?

Which of the following redox reactions do you expect to occur spontaneously in the forward direction under standard conditions? a. Ni (s) + Zn2 + (aq) →Ni2 + (aq) + Zn (s) b. Pb (s) + Mn2 + (aq) →Pb2 + (aq) + Mn (s) c.

Which of the following is a statement of hess's law? a) if a reaction carried out in a series of steps the, delta H for the reaction will equal the sum of the enthalpy changes for the individual steps.

Which of these statements about hydroelectric power is true? A. It uses civilization's earliest energy to produce electricity. B. It uses water's potential energy to produce electricity. C. It uses a safe, renewable resource. D.

Name an item scientist may use to observe with a camera, hand lens and microscope

Why does bromine not react with sulphur?

What happens to the size of the atom of anon-metal as it becomes an anion? A. it decreases B. it increases C. it remains the same D. it is impossible to tell unless you know the specific element

How is oxygen and nitrogen alike

Does a gas discharge tube filled with boron emit the same wavelength

a certain solution has a molarity of m = 6.39 mol/l and has a volume of v = 0.550 l what is the value of n