Why don't scientists know the exact number of species that have lived on earth

Based on what you know about speed of light and sound, which come/comes first in a thunderstorm

Which statement best explains the relationship between an area's geography and the temperature of its surface water? areas at low altitudes have the warmest water because they receive the most direct sunlight. areas at low altitudes have the warmest water because they have the least change in temperature throughout the year. areas at high latitudes have the warmest water because their days are the longest. areas at high latitudes have the warmest water because they have the longest seasons.

Which state in the united states founded the first true public zoo?