The minimum amount of energy necessary to start a chemical reaction is

activation energy

kinetic energy

enthalpy

entropy

A closed system is: completely closed to the outside environment. only slightly exposed to the outside environment. in constant exchange with the environment completely exposed to the outside environment.

You are on an island and need freshwater to drink. Which process could you use to separate the salt from ocean water and provide freshwater for drinking? O A. Distillation B. Chromatography C. Filtering O D. Freezing

The largest reservoir of carbon in the carbon cycle is in sedimentary rock that may take hundreds of millions of years to return to the living portion of the cycle. What is the second largest reservoir of carbon?

Which two elements make up water? oxygen and phosphorus oxygen and hydrogen hydrogen and sulfur hydrogen and phosphorush

How is a solute different from a solvent in a solution? a. The solute is present in a smaller amount. b. The solute is present in a greater amount. c. The solute is a solid and the solvent is a liquid. d.

Which physical method can be used for obtaining a sample of salt from a small beaker of salt water? boiling freezing chromatography sorting

Science is a unique field of thought because it relies on to describe the world. •Observations and experim •Teachers and students •Books and writings •Scientists and statements

Hemoglobin, a protein in red blood cells, carries o2 from the lungs to the body's cells. iron (as ferrous ion, fe2+) makes up 0.33 mass % of hemoglobin. if the molar mass of hemoglobin is 6.8 Ã 104 g/mol, how many fe2 + ions are in one molecule?

What could you predict about a methane molecule that would most likely be made by using both the quantum model of the atom and John Dalton's model?

What is the molar mass of an unknown hydrocarbon whose density is measured to be 1.97 g/l at stp?