What do these layers and their fossils suggest about Earth's history? ОА.
Lifeforms on Earth have been the same over time.
ОВ.
No lifeforms were present when these layers formed.
OC. Only one kind of lifeform lived where these layers formed.
OD
There have been changes in Earth's lifeforms over time.

In vapor-liquid equilibrium in a binary mixture, both components are generally present in both phases. how many degrees of freedom are there for such a system? the reaction between nitrogen and hydrogen to form ammonia occurs in the gas phase. how many degrees of freedom are there for this system? steam and coal react at high temperatures to form hydrogen, carbon monoxide, carbon dioxide, and methane. the following reactions have been suggested as being involved in the chemical transformation:

What is the percent by mass of magnesium sulfate in mgso4.7h2o

Which of the following are acids or bases? 1. sodium hydrogen 2. barium hydroxide solution 3. carbonate solution