A particular atom of calcium has 20 protons, 21 neutrons, and 19 electrons. what is the electrical charge on this atom?

Explain which of the following are correct statements of the Second Law of Thermodynamics and which are not. a. All reversible heat engines have the same efficiency. b. An engine connected to one heat reservoir can do work on the surroundings. c.

When a toaster in use electrical energy is transformed into

Sterling silver contains 92.5 percent silver and 7.5 percent copper. which substance is the solute?

Which of the following Period 4 elements has the most metallic characteristics? A) Ca B) Ge C) As D) Br

Name the ketone with a five carbon group on the right and a two carbon group on the left. View Available Hint (s) Name the ketone with a five carbon group on the right and a two carbon group on the left.

Lithium and nitrogen react in a combination reaction to produce lithium nitride: 6Li (s) + N2 (g) → 2Li3N (s) How many moles of lithium are needed to produce 0.60 mol of Li3N when the reaction is carried out in the presence of excess nitrogen?

7. Convert 5.2 cm of magnesium (Mg) ribbon to mm of Mg ribbon.

If you place a crystal substance on a tabletop, return to view it after some time passes, and find it as a powdered substance, which of the following processes most likely took effect? A. Efflorescence B. Distillation

What changes occur in the nuclei of atoms involved in the reactions that fuel nuclear power plants?

Calculate the molar mass for HCN. 0.2703 g/mol 2.703 g/mol 27.03 g/mol 270.3 g/mol