What defines an exothermic reaction?

O A. A reaction that needs heat added

O B. A reaction that possesses enthalpy

O c. A reaction that relies on collisions

O D. A reaction that produces heat

Which of the following statements are true about the international system of measurement?

In the formation of potassium chloride, the product, KCl, has less energy than the reactants, K and Cl2. This reaction is.

How many atoms of each element are in the chemical formula Ca (OH) 2? a) 1 calcium, 1 oxygen, and 1 hydrogen b) 1 calcium, 2 oxygen, and 2 hydrogen c) 2 calcium, 1 oxygen, and 2 hydrogen d) 2 calcium, 2 oxygen, and 2 hydrogen

Select the correct answer. What energy does a rock resting on a hilltop store? A. gravitational energy B. chemical energy C. thermal energy D. nuclear energy E. radiant energy

What holds earths atmosphere in place

For what reasons would modern scientists accept dalton's atomic theory but not the idea of an atom proposed by the greek philosophers?

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?