1. An airplane flew from San Francisco to Washington, D. C.
Approximately halfway through the flight, the plane had traveled 2,000
km in 2.5 hours. What was the speed during this period?

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation:

explanation:

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante

d) a person who learns about the world by observing it.

explanation:

scientist are people who discover why and how things are done and made in the world.