11. After balancing the following redox reaction in an acid medium: Zn2+(aq) + MnO2(s) → Zn(s) + MnO4⁻(aq), indicate whi

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11. After balancing the following redox reaction in an
acid medium: Zn2+(aq) + MnO2(s) → Zn(s) + MnO4⁻(aq), indicate which
is the reducing agent:
a. MnO2
b. Zn2+
c. zinc
d. MnO4⁻
12. The average rate at which a zone of solute migrates
down the column is inversely proportional to:
a. dead time
b. retention time
c. column length
d. the resolution
14. Compounds A and B absorb in the ultraviolet region
at 312 nm and 267 nm. At 312 nm, the molar absorptivities of A and
B at 312 nm are 120.6 M-1 cm-1 and 1860 M-1 cm-1, respectively. The
absorptivity of A at 267 nm is 1570 M-1 cm-1. In a cell with a path
length of 1.00 cm, the absorbances of the mixture of compounds A
and B were 0.726 and 0.544 at wavelengths of 267 nm and 312 nm,
respectively. Which of the following situations shows the effect of
the concentrations of substances A and B in the
mixture?
a. The concentration of A does not depend on the concentration
of B at 267 nm since B does not absorb at that wavelength.
b. In the absorption spectrum a band will appear at 267 nm
representative of species B.
c. The concentration of B depends on the concentration of A at
312 nm with a total absorbance equal to 1.27.
d. The concentration of A depends on the concentration of B at
312 nm with a total absorbance less than that at 267 nm
18. Which of the following represents the application of
a technique for the quantitative determination of an analyte in a
sample?
a.process
b. method
c. technique
d.analysis