. Which can occur during a physical change? (Select all that apply.)

The shape of a piece of matter can change.

The chemical reaction produces a new substance.

The atoms of the substance can permanently change.

The amount of energy within a substance can change.

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.

How many moles are contained in 5.6 l of h2 at stp

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