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?

How many moles of hydrogen atoms are present in 25.0 g of water?

Describe the three subatomic particles (protons, neutrons, and electrons) in terms of their mass, charge, and location within the atom.

If the wavelength of one wave is 0.25 or ¼ meters, how many waves will be formed in one meter?

What is a qualitative observation

Is the combustion of gasoline endothermic or exothermic?

The water level in a graduated cylinder stands at 20.0 ml before and at 26.2 ml after a 16.74 g metal sample is lowered into the cylinder. what is the density of the sample. what metal is the sample most likely to be

What are the tube feet on a star fish

What kingdom is humans in!

Propane (C3H8) has a molar mass of 132 g/mole. You started out the day with a tank containing 9071 g of propane. At the end of the day, your tank contained 7532 g of propane gas. How many moles of gas did you use?

Why decomposition of ammonium nitrate is a redox reaction?