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A radioactive isotope has a half-life,  t½ = 27.3 yr.How long will it take for a 3.27 mCi sample of this isotope to decay to 0.351 mCi? a. 0.0817 yr b. 38.2 yr c. 133 yr d. 87.9 yr e. 60.9 yr

What is [H+] when pOH = 8.3?   a. 2.0 x 10-6 M b. 5.0 x 10-9 M c. 3.3 x 10-3 M d. 5.7 M e. 5.0 x 105 M

What is the charge of Cr in the complex : [Cr(SO4)2(C2O4)2]-5?a. +5 b. +2 c. +3 d. +1 e. -3

Calculate Eocell for the following balanced redox reaction in acidic solution: 3 SO-24 + 2Cr(s) + 12 H+ → 3 SO2 (g) + 2Cr+3 + 6 H2O (acidic)  a. +1.945 V b. -0.585 V c. +0.585 V d. -0.895 V e. +0.895 V

Classify NaOH as a strong base, weak base, strong acid, or weak acid. Then answer the following question. What is the pH of a 7.8 x 10-5 M NaOH(aq) solution? a. 4.1 b. 9.5 c. 9.9 d. 4.5 e. 13.0

Consider the following data for the reaction: A + B → products [A] [B] Rate 0.2 M 0.1 M 20 M/s 0.4 0.1 80 0.4 0.2 320 What is the rate law? (Suggestion: first determine the order in both A and B by the ratio technique.) a. Rate = k[A]2 b. Rate = k[A][B] c. Rate = k[A][B]2 d. Rate = k[A]2 [B]2 e. Rate = k[A]2 [B]   Tables.pdf Periodic Table with New Elements.pdf

What [Ag+] is needed to begin precipitating Ag2SO4 (s) from a 0.092 M SO4-2 solution? Ksp of Ag2SO4 = 1.6 x 10-5 a. 1.3 x 10-2 M b. 1.2 x 10-3 M c. 8.7 x 10-5 M d. 1.7 x 10-4 M e. 6.6 x 10-3 M

What is the Ka expression for HClO2?   a.

Suppose a solution contains 0.7 M Ba2+ (aq) and 0.4 M Mg2+ (aq). Fluoride ions, F- , are then slowly added to the solution.  At what [F-] will MgF2 (s) start to precipitate? (Suggestion: Write the dissolving equation and Ksp expression for MgF2 before starting this problem.) a. 1.3 x 10-5 M b. 1.8 x 10-10 M c. 1.0 x 10-5 M d. 6.6 x 10-6 M e. 1.9 x 10-5 M   Tables.pdf Periodic Table with New Elements.pdf

Consider the following data for the reaction: A → product [A] Initial Rate 0.03 M 4.69 x 10-5 M/s  0.17 2.66 x 10-4 0.46 7.19 x 10-4 0.73  1.14 x 10-3 What is the rate law? (Hint: use the “ratio technique”) a. Rate = k[A] b. Rate = k/[A] c. Rate = k d. Rate = k/[A]2 e. Rate = k[A]2