When do elements absorb energy and enter an excited state?

What happens when a piston is used to decrease the volume of a contained gas? a. Fewer gas particles exert a force on the piston. b. The piston's pressure on the gas becomes greater than the pressure exerted by the gas on the piston. c.

3.7 grams of aluminum combine with excess copper (II) sulfate with 10 grams of copper produced. What is the percent yield? The equation is balanced below. 2Al + 3CuSO4 - -> Cu + Al2 (SO4) 3

Which of the following, when dissolved, will cause water to reach the highest temperature before boiling? A. Epsom Salt (MgSO4) B. Potassium sulfide (K2S) C. Sodium Chloride (NaCl) D. Sugar (C6H12O6)

What is true about the mass of protons and neutrons? A) They are exactly equal to each other. B) They are exactly equal to 1 amu. C) They have negligible mass. D) They have masses slightly greater than 1 amu.

Which planet likely has flowing liquid metallic hydrogen as the source of its magnetic field?

Cation a has a + 3 charge and is small. cation b has a + 1 charge and is large. which is more likely to occupy negatively charged sites on a clay mineral given equal concentrations in solution? cation a cation b they are the same

Show your work, including units, for the following series of calculations: a. How many moles of Al are in 1.25 g of Al? b.

An aqueous solution at 25 °C has a pOH of 12.42. Calculate the pH. Round your answer to 2 decimal places

A student records the mass of a piece of iron. The iron is then left outside until it rusts. What type of reaction occurs, and how does the mass of the object after rusting compare with its original mass?

Which one is a true statement about endothermic reactions? A. Energy from an outside source is continuously being added. B. More heat is given off than is put into the reaction. C. The reactants have less heat energy than the last products. D.