Which of these is a demonstration of a chemical change? A. ice melting into water B. wood becomes charred and black from burning C. water evaporates from a sugar solution, leaving behind sugar crystals D. a balloon suddenly popping

A 220.0-mL sample ofhelium gas is in a cylinder with a movable piston at 105 kPa and 275 K. The piston is pushed m until the sample has a volume of 95.0 mL. The new temperature of the gas is 310. K. What is the new pressure of the sample?

An atom of sodium has an atomic mass of 23 and an atomic number of 11. The atom contains

Which statement correctly evaluates the results of the report? It is likely to be reliable because the tests were done in a laboratory. It is likely to be reliable because the results support the conclusion presented.

Which of the following best defines an acid? A) An acid has a pH of 7. B) An acid has hydroxide ions. C) An acid has fewer positive ions in solution. D) An acid has more hydrogen ions in solution.

What happens when you add phenolphthalein to water?

Density differences cause the

Why can't you balance a chemical equation by changing the subscript?

Which level of organization is best represented by the corn plant? tissue, the highest level of organization organ, the lowest level of organization organism, the level of organization directly above organ system organ system, the level of

What is one product of a condensation reaction between two amino acids, such as glycine and alanine?

A solution is made by dissolving 25.20 g of aluminum acetate in 185.0 mL of water. What is the concentration of acetate ions?