What are “condensation nuclei”?

Which statement is usually true about the relationship between activation energy and reaction rates? low activation energy barriers result in low rates. high activation energy barriers result in low rates. low activation energy barriers result in no reaction. high activation energy barriers result in no reaction.

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?

Which of the following elements would you expect to have the highest ionization energy value, and why? a. chlorine (cl), because it has a low effective nuclear charge and large radius b. fluorine (f), because it has a large radius and naturally forms a negative ion c. lithium (li), because it has a small radius and naturally forms a positive ion d. neon (ne), because it has a high effective nuclear charge and small radius