A substance undergoes first order decomposition.  After 180.0 minutes, only 3.125% remains.  What is the half life for this substance?   A. 18 minutes B. 36 minutes C. 72 minutes D. 90 minutes

The following shows the titration of Acetic acid (CH3CO2H) with Sodium Hydroxide (NaOH).  Which species dictates the pH of the solution when 50 mL of NaOH has been added?   A. CH3CO2H B. CH3CO2H and CH3CO2- C. CH3CO2- D. OH-

Which atom has the most metallic character? A. Carbon (C) B. Cobalt (Co) C. Chromium (Cr) D. Rubidium (Rb)  

For lactic acid, C3H5O3H, Ka = 1.4 x 10-4.  What [C3H5O3-]/[C3H5O3H] ratio results in a buffer with a pH of 4.00? A. 0.70 B. 1.2 C. 1.4 D. 1.8

Consider the following endothermic reaction: 3NO(g)  ⇌  N2O(g)  +  NO2(g) Which process would increase the product concentration for this reaction? A. Decrease the temperature B. Add a catalyst C. Decrease the concentration of NO gas D. Remove NO2 gas

A voltaic cell employs the following redox reaction: Sn2+ (aq)  +  Mn (s)  

What are the correct classifications for I, II and III?                   I                             II                           III A.   compound               element                 mixture B.    element                   mixture               compound C.    mixture                   element                compound D. compound                mixture                   element

Consider the reaction:   2NO(g)  +  O2(g)  →  2NO2(g)             If the rate of appearance of nitrogen dioxide is 0.040 mol·L–1·s–1, then what is the rate of disappearance of O2? A.   –0.040 mol·L–1·s–1 B.   –0.020 mol·L–1·s–1  C.  –0.010 mol·L–1·s–1  D.  –0.060 mol·L–1·s–1  

What is the net ionic equation for hydrochloric acid and sodium hydroxide?   A. HCl (aq)  +  NaOH (aq)  

The changes in Gibbs free energy,