Burning logs in the fire place produce heat energy. The dog gets warm from the fire when heat energy is transferred by A) the air. B) radiation. C) conduction. D) the flames.

Use the standard enthalpies of formation for the reactants and products to solve for the δhrxn for the following reaction. (the δhf of c2h4 is 52.26 kj/mol, co2 is -393.509 kj/mol, and h2o is -241.818 kj.) c2h4 (g) + 3o2(g) 2co2 (g) + 2h2o(g) δhrxn = the reaction is .

Embryos of different species look very similar, which shows that the organisms share a ancestor.

Why are the trends and exceptions to the trends in ionization energy observed?