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Which of the following statements concerning oxidation numbers is true?

Consider the reaction below:    Mg(s) + 2 HCl (aq) → MgCl₂ (s) + H₂ (g)   In this reaction,                    is oxidized and                     is reduced.

You wish to make 500.0 mL of a 0.125 M solution of CaCl2. What volume (in mL) of the more concentrated 3.50 M solution of CaCl2 is required to make this solution?

Which of the following processess has a negative ΔH (exothermic)?

Given the following data:                      2 C (s)  +  O2 (g)  →  2 CO (g)                 ΔH =   −221.0 kJ      2 C (s)  +  O2 (g)  +  4 H2 (g)   →   2 CH3OH (g)     ΔH =  −402.4 kJ     Calculate ΔHrxn  for the reaction:      CO (g)    +  2 H2 (g)   →    CH3OH (g)

A  260/280 ratio should be 1.6 and 2. What is happening when the ratio is less than 1.6?

Data redundancy is having the same data stored in multiple locations. Does the database approach minimize/reduce or maximize/increase this?

Examine the following tables. Assume that the Student Table has hundreds of students in it, three of which you see below.Assume that the Professor Table has hundreds of professors in it, three of which you see below.Assume that the Class Table has hundreds of classes in it, three of which you see below.Based upon these assumptions, you are seeing the first three records found in each table and the table has more records in it than what you see. Question: Which of the following fields would be considered a foreign key?

What formatting error is seen in the image below?

Which of the following is the BEST primary key that you might use?