A 0.0727-g sample of an unknown metal (X) reacted with hydrochloric acid according to the following chemical equation: 2 X (s) + 6 HCl (aq) →2 XCl3 (aq) + 3 H2 (g) The volume of hydrogen gas collected over water was 99.0 mL at 22°C and 770 mm Hg. Calculate the atomic mass of the unknown metal and identify the metal from the periodic table.

Idon’t know how to solve this question

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

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.