Which of the following isotopes is radioactive A) C-12 B) Pb-206 C) Tc-99 D) Ne-20

How long is a half life for carbon 14?

Which natural polymers are involved with making clothing? wool, silkworm cocoon, and cellulose wool, nylon, and DNA starch, nylon, and DNA starch, silkworm cocoon, and cellulose

Wes melted some cheese over some tortilla chips to make nachos. How is the melted liquid cheese different from the solid cheese? A. It has a different shape. B. It has a different flavor. C. It has a different color. D. It has a different mass.

1) If the average atomic mass of hydrogen in nature is 1.0079, what does that tell you about the percent composition of H-1 and H-2 in nature?

HC1 solution is mostly water. NaOH solution is mostly water. When 50mL of HC1 is mixed with 50mL of NaOH, what is the final mass?

A 10 pound block of lead-210 has a half-life of 22 years. What percentage of the block still contains lead-210 after 60 years? 1.5% 15% 77% 27%

Combined gas law problem: a balloon is filled with 500.0 mL of helium at a temperature of 27 degrees Celsius and 755 mmHg. As the balloon rises in the atmosphere, the pressure and temperature drop.

1. What hypothesis could you propose about the relationship between the position of a type of atom in a molecule and the number of bonds that the atom forms? Explain your thinking.

The molality of a solution is a measure of - A - moles of solute per kilogram of solution B - moles of solute per liter of solution C - moles of solute per kilogram of solvent D - moles of solute per liter of solvent

Which technology has allowed for exploration beyond our solar system? A) space probe B) space station C) space shuttle D) space observatory