Which of these is an example of a chemical change?

ironing a shirt

grinding powder

melting cheese

fireworks exploding

A mixture was found to contain 1.05g of sio2, 0.69g of cellulose, and 1.82g of calcium carbonate, what percentage of calcium carbonate is in the mixture

If ATP is hydrolyzed in a test tube, which of the following effects indicates that the reaction is exergonic? A) Release of energy drops the temperature in the test tube. B) Release of energy has no effect on the surroundings.

If the quantity of heat lost or gained is (ΔH) = mass * change in T * specific heat, what is the amount of heat required to raise 200.0 g of water from 22.00°C to 100.0°C? The specific heat of water is 4.180 Joules per gram-°C.

Which radioisotope has an atom that emits a particle with a mass number of 0 and a charge of + 1? (1) 3H (3) 19Ne (2) 16N (4) 239Pu

An unknown substance in aqueous solution is treated with various reagents including hexane, a colorless liquid less dense than water. The test tube is stoppered and shaken. The upper layer remains colorless.

List at least two chemical reactions that resulted in a yellow, orange, or red precipitate. For these reactions, list the possible chemical name of the precipitate.

You place air in a sealed can at stp. ypu triple its absolute temperture (K) while leaveing the volume constant. what happenes to the pressure

A current of 10.4 a is applied to 1.25 l of a solution of 0.552 m hbr converting some of the h + to h2 (g), which bubbles out of solution.

What is a greenhouse gas?

Which statement best describes a mole?