Which of the following is not evidence of a chemical change?

A. a change in color

B. the production of a gas

C. the formation of a precipitate

D. the separation of particles

Determine the empirical formula of an organic hydrocarbon compound that contains 80% by mass of carbon and 20% by mass of hydrogen. If the Mr of the compound is 30, what is the molecular formula?

What is the mass of CO2 in atomic mass units? 28 amu 44 amu 12 amu 22 amu

An atom has atomic number 11 and mass number 23. How many electrons does the atom have?

Why must living things rely on thousands of catalysts for chemical reactions necessary for life?

Explain different between subscripts and coefficients

Why electrons are transferred during the course of the reaction between magnesium and oxygen?

Human muscle stores sugars in the form of

How much heat is needed to raise the temperature of 75 g of a substance by 15 C when the specific heat is 0.92 J/g-C?

A nitric acid solution flows at a constant rate of 5L/min into a large tank that initially held 200L of a 0.5% nitric acid solution. The solution inside the tank is kept well stirred and flows out of the tank at a rate of 10L/min.

How many molecules are in 237g (about a cup of water)