List two observations that could be evidence of a chemical reaction.

Select the correct answer. Which of the following is necessary to increase the rate of a reaction? A. a decrease in the frequency of collisions B. an increase in the frequency of collisions C. a decrease in the frequency of successful collisions D.

How much heat is absorbed by a 72g iron skillet when its temperature rises from 80C to 260C?

Explore this interactive illustration by clicking through the presentation on the movement of Earth's tectonic plates through time. The continents of Africa and South America used to "fit together" like puzzle pieces.

Of the choices below, which is true for the relationship shown? a. It is Ka for the acid H3P2O72-. b. It is Kb for the acid H3P2O72-. c. It is Ka for the acid H2P2O72-. d. It is Kb for the acid H2P2O7

In polypeptide met-phe-leu, what amino acid has a free carboxyl group?

Sodium metal reacts with water to form aqueous sodium hydroxide and hydrogen gas. which equation below best describes the balanced equation for this reaction?

2H2 + O2 - - > 2H2O If 16 mol of oxygen were reacted with excess hydrogen gas, how many moles of water would be produced?

Which subatomic particle identifies an atom as that of a particular element? how is this particle related to the atoms atomic number

Which of the following prefixes means seven

Which of the solutions below is a weak electrolyte? nacl (aq) koh (aq) hcl (aq) h2so3 (aq) all of these?