46) If the calibration unit of a buret is 0.1 ml, to what precision can you meas

Question

46) If the calibration unit of a buret is 0.1 ml, to what precision can you measure this buret? A. to the nearest 1 ml B. to the nearest 0.1 mL C. to the nearest 0.01 mL D. to the nearest 0.001 mL. 47) What is a Lewis acid? A. a chemical species that accepts a proton B. a chemical species that donates a proton C. a chemical species that accepts a pair of electrons D. a chemical species that donates a pair of electrons 8 48) What is the voltage of a Zn/Cu Galvanic cell in which the Zn2 and Cu" concentrations are both 0.10 M? A. 1.00 V B. 1.05 V C. 1.10 V D. 1.15 V 49) How did you determine the amount of vitamin C in lab? A. Reaction with excess potassium iodate, KIO. B. Reaction with excess sodium thiosulfate, Na2S203. C. Reaction with excess iodine, 12 D. Reaction with excess sulfuric acid, H2SO4. 50) The mass of a nucleus was found to be 0.0237 amu less that the mass of all its nucleons added together. What is binding energy of this nucleus? A. 3.54 x 1o12 Joule B. 3.54 x 109 Joule C. 3.94 x 10 Joule D, 3.94 x 106 Joule

Explanation / Answer

46) If the calibration unit of the buret is 0.1 ml, a rule of thumb says we can read the value to a precision of +/- 0.1/10 ml = +/- 0.01ml. Therefore the answer is option C

47) Lewis acid is the compound that accepts a pair of non bonding electrons. Therefore the answe is option C

48) Voltage of Zn/Cu cell:

The reduction reaction is: Cu2+ + 2e- ------> Cu Eo = +0.34V

The oxidation reaction is: Zn ------> Zn2+ + 2e- Eo = +0.76V

Eocell = Eoreduction + Eooxidation = 0.34+0.76 = +1.10V

The Redox reaction is:

Zn + Cu2+ ------> Zn2+ + Cu

Now,

Ecell = Eo - 0.059/n log( [C]c[D]d/[A]a[B]b )

= 1.10 - 0.059/2 log([Zn2+]/[Cu2+])

Here both the concentrations are equal to 0.10M, so the Ecell = Eocell = 1.10V

Therefore the answer is option C

49) Vitamin C or ascorbic acid is determined by dissolving pottassium iodate in water and titration. With starch in the solution any excess Iodine or Iodate will form a blue black complex with the starch indicating the end point of the titration. The option is A

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