What are the electronic configurations for the first twenty elements

Before a bond breaks in a chemical reaction, what happens

A sample of oxygen gas is sealed in container X. A sample of hydrogen gas is sealed in container Z. Both samples have the same volume, temperature, and pressure. Which statement is true? (1) Container X contains more gas molecules than container Z.

A mixture of BaCl2 and NaCl is analyzed by precipitating all the barium as BaSO4. After addition of an excess of Na2SO4 to a 3.988-g sample of the mixture, the mass of precipitate collected is 2.113 g.

Which of the following is true for compounds? A. They all have the same properties regardless of their elemental composition. B. They can be created by chemical reactions. C. They can consist of no more than two types of elements. D.

Which of the following would most likely act as a Bronsted-Lowry acid?

How many milliliters of a 0.7% stock solution are required to make 2 l of 0.2% solution? how many ml of solvent will be required to carry out the dilution?

What percentage of the naphthalene molecules emitted a photon?

In an endothermic reaction, heat is absorbed from the surroundings. How does this affect entropy? A. The particles in the surroundings move slower and have decreased entropy. B.

The temperature of a sample of liquid water changes from 50°C to 30°C. Which statement best explains the change that must happen at the molecular level? A. The molecules move more quickly and their average kinetic energy increases. B.

The most important reason why solid sodium hydroxide is not used as a primary standard is