Which of these events happens first in earth's polar regions?
a. the dense water sinks.
c. water molecules move closer together.
b. the water travels as a deep current.
d. cold air chills water molecules.

Creation of an unnaturally uniform sample to represent a diverse populationcan be avoided by: a. including only willing b. asking another scientist for .c. choosing only identical participants.d. selecting individuals at random.

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

Vinegar has a ph of 3, and household ammonia has a ph of 11. is the concentration of h+ greatest in the vinegar or ammonia?