You start with a 500 g sample of Co-57. about how much time has passed if you end up with a 250 g sample

Which two notations represent atoms that are isotopes of the same element? a. 12150sn and 11950sn b. 12150sn and 12150sn c. 198o and 199f d. 3917cl and 3919k?

balance the following reaction. a coefficient of "1" is understood. choose option "blank" for the correct answer if the coefficient is "1". ___ Kcl + ___ Pb (NO3) 2 - ->___ Pbl2 + ___ KNO3

What will happen to the gas pressure as the temperature increases, if the amount and volume of the gas are kept constant?

What do you know about two atoms if their atomic numbers are different

Consider the steps in a bicycle-factory assembly line: Step 1: rate = 120 handlebars per hour Step 2: rate = 60 sets of wheels per hour Step 3: rate =

Which physical method can be used for obtaining a sample of salt from a small beaker of salt water? boiling freezing chromatography sorting

Science is a unique field of thought because it relies on to describe the world. •Observations and experim •Teachers and students •Books and writings •Scientists and statements

Hemoglobin, a protein in red blood cells, carries o2 from the lungs to the body's cells. iron (as ferrous ion, fe2+) makes up 0.33 mass % of hemoglobin. if the molar mass of hemoglobin is 6.8 Ã 104 g/mol, how many fe2 + ions are in one molecule?

What could you predict about a methane molecule that would most likely be made by using both the quantum model of the atom and John Dalton's model?

What is the molar mass of an unknown hydrocarbon whose density is measured to be 1.97 g/l at stp?