An enzyme that catalyzes addition or removal of hydrogen or ...

[charchew]

An enzyme that catalyzes addition or removal of hydrogen or oxygen on substrate molecules is a(an) ________.
 
  A) ligase
  B) isomerase
  C) oxidoreductase
  D) transferase
  E) hydrolase

Question 2

Lead ions can be precipitated from aqueous solutions by the addition of aqueous iodide: Pb2+(aq) + 2I-(aq)  PbI2(s) Lead iodide is virtually insoluble in water so that the reaction appears to go to completion.
 
  How many milliliters of 3.550 M HI(aq) must be added to a solution containing 0.700 mol of Pb(NO3)2(aq) to completely precipitate the lead?
  A) 2.54  10-3 mL
  B) 394 mL
  C) 197 mL
  D) 0.197 mL
  E) 0.394 mL

Question 3

To prepare a buffer using sodium phosphate, which of the following would also be needed?
 
  A) hydrochloric acid
  B) ammonium hydroxide
  C) ammonium phosphate
  D) phosphoric acid
  E) sodium hydroxide

[cloud]

Answer to Question 1

C

Answer to Question 2

B

Answer to Question 3

D

[charchew]

Great answer, keep it coming

[yeungji]

Gracias!