Abox has a weight of 248g and the bottom of the box is 30.48cm^2.what is the pressure the box exerts on the floor?

Asample of radium-226 will decay 1/4 of its original amount after 3200years. what is the half-life of radium-226?

As changes in energy levels of electrons increase, the frequencies of atomic line spectra they emit

Hydrogenation reactions, in which h2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. in the simplest case, ethene (c2h4) and h2 form ethane (c2h6). if 140 kj is given off per mole of c2h4 reacting, how much heat (in mj) is released when 12 kg of c2h6 forms?