Which best describes a mixture

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

Water (2510 g ) is heated until it just begins to boil. if the water absorbs 5.09×105 j of heat in the process, what was the initial temperature of the water?

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?