A sample of a radioactive isotope initially contains 20 x 10^10 atoms. After 16 days, 5 x 10^10 atoms remain. what is the half-life of the isotope?

A) 12 days

B) 20 days

C) 10 days

D) 16 days

E) 8 days

How many moles are in 35.0 grams of H₂O?

Name two elements that go through alpha decay.

Which one of these is an example of cell division at work

When an atom of phosphorus becomes a phosphide ion (P3-), the radius (1) decreases (2) increases (3) remains the same?

Why is seawater a mixture

If a sample containing 2.50 ml of nitroglycerin (density=1.592g/ml) is detonated, how many total moles of gas are produced?

A helium balloon initially at room temperature is dunked into a bucket of liquid nitrogen (T = 77 K). Which of the following will occur?

Which statements indicate what the fossil record suggests about evolution on Earth? Check all that apply. Humans have only recently existed on Earth. Organisms originally lived only in Earth's water. Life on Earth started when water formed on Earth.

What does homogeneous mixture of elements mean

As an acid is added to neutral water the [OH-] will