A what is the part that doesn't change during the experiment

If a sample of radioactive isotopes takes 600 minutes to decay from 400 grams to 50 grams, what is the half-life of the isotope?

The goal of this experiment was to answer the question "what is the effect of a gas' temperature on its volume? " you formulated the hypothesis below. hypothesis: if a fixed amount of gas is heated, then the volume will increase because the heat will cause the molecules of gas to move faster and further apart. to test this hypothesis, you changed the of the gas between 0 and 100°c (273 and 373 k) and calculated the resulting of the gas.

How to convert 76.6lb to pounds? need asap