In which period do potassium and calcium lie in the Modern periodic table

Which statement is true about a catalyst? a: a catalyst decreases the rate of the reaction. b. a catalyst is consumed during a chemical reaction. c. a catalyst lowers the activation energy of a reaction. d. a catalyst increases the reactant concentration during a reaction.

How many moles are in 7.2 x 10^23 carbon molecules?

The temperature of a lead fishing weight rises from 26 °c to 38 °c as it absorbs 11.3 j of heat. what is the mass of the fishing weight in grams?