In a reaction between gases, the reaction rate can be increased by -
a. increasing volume.
b. adding a catalyst.
c. lowering temperature.
d. decreasing pressure.

weathering is the answer.

b brown mice / white sand dunes

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex