Which of the following involves a reaction in which energy is absorbed? O A. An instant cold pack
O B. A car's engine
C. A chemical hand-warmer
O D. A campfire

Which of the following is most likely true about water in chemical solutions?

How does a catalyst increase the speed of a reaction? a. the catalyst eliminates the activated complex stage, allowing products to form immediately. b. the catalyst lowers the energy level of the reactants, making it easier for them to react. c. the catalyst makes it easier for the activated complex to form, lowering the activation energy. d. the catalyst raises the energy level of the products, making the reaction finish sooner. reset next

An unknown substance has been shown to have weak covalent bonds. which of the following is most likely a property of this substance? a. high ph b. high conductivity c. low melting point d. low flammability