When the moon is directly between the sun and the earth which phase of the moon is seen on earth

Joan writes four numbers on the board in standard form, and then she writes their scientific notation

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

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.