Which of the following is a chemical change? a. silver tarnishing as the silver metal reacts with sulfur b. a rock eroding as the wind removes particles from it c. soil drying as water evaporates d. a solution of acid being diluted as water is added to it

The diagram shows the structures of horse and cat forelimbs. what does the diagram suggest about the evolutionary relationship between these two mammals? a. they have homologous structures, indicating a common ancestor. b. they have analogous structures, indicating a common ancestor. c. they have homologous structures, indicating that they do not have a common ancestor. d. they have analogous structures, indicating that they do not have a common ancestor.

1) these are barrel shaped microtubules in most animal cells, that organize the spindles during cell division

Calculate the molar mass of aluminum oxide (al2o3). express your answer to four significant figures.