Defition of chemical change

Knee pads are the most important protective piece of equipment when riding a bike. True False

Which organisms form the base of all ecosystems? Select one: a. scavengers b. producers consumers d. decomposers

If 2 CH3OH + 3 O2 - > 2CO2 + 4 H2O was carried out in the laboratory and 219 g of water was produced, what would the percent yield be if the reaction started with 229 g of methanol in excess oxygen gas

When a scientist serves in an advisory role to society, he or she must

One of the isotopes of sulfur is represented as sulfur - 35 or S-35. what does the number 35 signify?

Which of the following are physical properties of a penny? Choose all that are correct. Select one or more:a. Slightly red in color. b. Conducts electricity very well. c. Reacts to oxygen when heated. d. Resists corrosion from most acids.

NO2 and N2O4 undergo the reaction shown. When a sealed container of NO2 reaches chemical equilibrium, which must be true? A) No N2O4 is present. B) No chemical reactions are occurring. C) The rates of the forward and reverse reactions are equal.

What differences did you notice in the different states of water

1. Bubbling or fizzing is an indicator of a. property change b. phase change c. physical change d. chemical change

In the second step of this reaction, isocyanic acid reacts to form melamine and carbon dioxide: HNCO (l) →C3N3 (NH2) 3 (l) + CO2 (g) Balance this reaction and enter the coefficients below.