Why isn't the atomic mass of most of the elements on the periodic table a whole number?

There is a 30 g sample of Be-11. It has a half-life of about 14 seconds. How much will be left after 28 seconds? A. 3.75 gB. 7.5 gC. 15 gD. 30 g

Write a net ionic equation to show that nitrous acid behaves as a brønsted-lowry acid in water.

How can the same species of fossil be found on different continents

In a system in which the enthalpy changed - 447.1 kJ/mol and the entropy decreases by 75.1 kJ/mol•K, calculate the temperature at which the system will be at equilibrium.

The sun produces energy by the process of nuclear: fission fusion

Which substance is the oxidizing agent in this reaction? 2CuO+C→2Cu+CO2 Express your answer as a chemical formula.

Why does the light bulbs have to be part of the loop in order for it to be succesful?

Which best describes the transition from gas to liquid? Energy must be removed because particles in liquid move more slowly. Energy must be added because particles in liquid move more quickly.

Calculate the mass of a 0.255-ml sample of a liquid with density 0.660 g/ml.

Which statement correctly describes the interaction between magnetic poles? North and south poles attract each other. North and south poles repel each other. Two north poles will attract each other. Two south poles will attract each other.