When 12.4 grams of KBr are dissolved in enough water to create a 170-gram solution, what is the solution's concentration, expressed as a percent by mass?

After leaving the cockroaches in their metabolic chamber for one hour the gases in the chamber was measured. The fraction of oxygen in the chamber was 0.18.

Explain the importance of saponification.

What is composed of more than 200 billion stars including the sun

In the ground state, an atom of each of the elements in Group 2 has a different 1. oxidation state 2. first ionization energy 3. number of valence electrons 4. number of electrons in the first shell

Which of the following processes does not involve a change in chemical properties? Rusting fermenting burning boiling

Identify each enthalpy change by name and classify each change as exothermic or endothermic. 1. 1 mol NaCl (s) à 1 mol NaCl (l) 2. C4H10 O (l) à C4H10O (g) 3. H2O (g) à H2O (l) 4. 1 mol NaCl (s) + 3.

Calculate the number of atoms in a 1.26*103 g sample of silicon.

A region that has a large number of atoms whose magnetic fields are lined up parallel to a magnet's field is A. the magnetosphere. B. the magnetic declination. C. a magnetic domain. D. a ferromagnetic region.

Name the element that has atoms with the same electronic structure as sulfur ion

The mass of a 2.0 centimeter sample of a substance is 3.2 grams. Calculate the density of the substance