Which of the following is not a potential sign of a chemical change?

a) release of gas

b) evaporation of water

c) change of color

d) production of gas

Which organic compound is saturated? 1. ethene 2. propene 3. ethyne 4. propane

A 20.0 g sample of a compound of nitrogen and oxygen contains 7.37 g of nitrogen. what is the formula of this compound?

Melanie completes a long distance run at an average speed of 6 mph. If it takes her 3 hours, how much fat did she run?

If your lab procedure instructs you to add two parts of acid to each one part of water and you start with 25 ml of water, how much acid will you add, and how will you add it

56. A gas has an initial volume of 2.50 L and temperature of 45 °C. What is the temperature if the volume is changed to 1.80 L?

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?