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A Lewis Dot structure with placeholder elements is shown. Given that the formal charge on the central atom is zero, which of the following are its possible identities? 

What is the molar mass of vanadium (III) hydroxide?

Consider the hypothetical reaction: A + 2B  → C + 2D.  Calculate ΔHrxn (in kJ/mol) for the reaction given the following information:      D → A + C ΔH = 80 kJ/mol 0.5 D + C → B ΔH = –10 kJ/mol

Consider neutral atoms of potassium, sodium, and chlorine.

A “smoot” is a unit of length originated as a joke at MIT in the 1950’s. One smoot, defined as the height of its originator (Oliver Smoot) is equivalent to 1.700 m. Convert a distance of 0.0205 miles into units of smoots, including to the correct number of significant digits.

How many neutrons are in 51Cr3+ ?   [27] How many electrons are in 86Sr2+ ?  [36]

Which has the LARGER mass?

Consider two solutes, Solute A (Molar Mass = 40 g/mol) and Solute B (Molar mass = 80 g/mol). Which of the following solutions has the greatest molar concentration? 

A and B react according to the following equation: 2A + 3B ⟶ C. How many moles of B are required to react with 5.0 moles of A?  For credit, enter your answer to the correct number of significant digits.

Which of the following chemical equations is NOT balanced?