Selenium-81 has an abundance of 21.91% and a mass of 80.65 amu. Selenium-84 has an abundance of 23.35% and a mass of 83.67 amu.
Selenium-80 has an abundance of 54.74% and a mass of 79.64 amu.
What is the average atomic mass of Selenium according to these values?

Achemistry student needs to standardize a fresh solution of sodium hydroxide. he carefully weighs out of oxalic acid , a diprotic acid that can be purchased inexpensively in high purity, and dissolves it in of distilled water. the student then titrates the oxalic acid solution with his sodium hydroxide solution. when the titration reaches the equivalence point, the student finds he has used of sodium hydroxide solution.calculate the molarity of the student's sodium hydroxide solution. be sure your answer has the correct number of significant digits.

What is the ph of a solution that has a hydrogen ion concentration of 1.0 * 10 -9 m?

Most ionic compouds are crystalline solids at room temperature. true falseionic compounds are electrically neutral. true falseionic compounds generally have low melting points. true falsewhen melted, ionic compounds do not conduct electricity. true falsethe electrostatic attraction between an anion and a cation is an ionic bond. true false