Online Chemistry 101 Exam

15 Questions | Total Attempts: 71

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Online Chemistry 101 Exam


Questions and Answers
  • 1. 
    Which of the following very high solubility in water
    • A. 

      C6H6

    • B. 

      C2H5OH

    • C. 

      C6H5NH2

    • D. 

      C6H5OH

  • 2. 
    The solubility of a gas in a liquid depends on ________
    • A. 

      Tempreture

    • B. 

      Pressure

    • C. 

      Nature of the gas

    • D. 

      All of the above

  • 3. 
    A solution is said to contain 28% phosphoric acid by mass . what does this mean ?
    • A. 

      1 ml of this solution contains 28 g of phosphoric acid

    • B. 

      1 L of this solution has a mass of 28 g

    • C. 

      10 g of this solution contains 28 g of phosphoric acid

    • D. 

      The density of this solution is 2.8 g/ml

  • 4. 
    A solution is prepared by dissolving 23.7 g of CaCl2 in 375 g of water the density of the resulting solution is 1.05 g/ml . calculate the % by weight of CaCl2 in the solution described above
    • A. 

      5.94%

    • B. 

      6.32%

    • C. 

      0.0632%

    • D. 

      0.0594%

  • 5. 
    Molality is :
    • A. 

      Moles of solute / moles solvent

    • B. 

      Moles solute / Kg solution

    • C. 

      Moles solute / liters solution

    • D. 

      Moles solute / Kg solvent

  • 6. 
    Calculate the molrity of phosphoric acid in a solution that is 84% phosphoric acid and has a density of 1.87 g/ml
    • A. 

      12

    • B. 

      14

    • C. 

      16

    • D. 

      18

  • 7. 
    Which one of the following varies with tempreturre
    • A. 

      Molarity

    • B. 

      Mass percent

    • C. 

      Mole fraction

    • D. 

      Molality

  • 8. 
    A particular chemical reaction involves a single reactant. What is the order of the reaction if the rate increases by a factor of eight when the concentration of the reactant is doubled?
    • A. 

      0th order

    • B. 

      1st order

    • C. 

      2nd order

    • D. 

      3rdorder

  • 9. 
    Gaseous N2O5 decomposes according to the following equation: N2O5(g) -------> NO2(g) + 1/2 O2(g) The experimental rate law is -Δ[N2O5]/Δt = k[N2O5]. At a certain temperature the rate constant is k = 5.0 x 10-4/second. In how many seconds will the concentration of N2O5 decrease to one-tenth of its initial value?
    • A. 

      2.0 x 103 s

    • B. 

      4.6 x 103 s

    • C. 

      2.1 x 102 s

    • D. 

      1.4 x 103 s

  • 10. 
    At 350 K, a particular second-order reaction, consisting of a single reactant, A, has a rate constant equal to 4.5 x 10-3 s-1. If the initial concentration of A is 0.80 M, how many half-lives are required for the concentration of A to become equal to 0.10 M?
    • A. 

      1

    • B. 

      2

    • C. 

      3

    • D. 

      4

  • 11. 
    Consider the following chemical reaction: 2 H2O2(aq) ------> 2 H2O(l) + O2(g) If the average rate of disappearance of H2O2 over a certain time interval is 6.80 x 10-5 M s-1 what is the average rate of appearance of O2 during this same time interval?
    • A. 

      4.62 x 10-9 M s-1

    • B. 

      3.40 x 10-5 M s-1

    • C. 

      6.80 x 10-5 M s-1

    • D. 

      1.36 x 10-4 M s-1

  • 12. 
    Which of the following would be expected to affect the rate of a given chemical reaction? I. The reaction temperature. II. The concentration of the reactants. III. A catalyst
    • A. 

      I

    • B. 

      II

    • C. 

      I and III only

    • D. 

      I,II and III

  • 13. 
    A student determined the value of the rate constant, k, for a chemical reaction at several different temperatures. Which of the following graphs of the student's data would give a straight line?
    • A. 

      K versus T

    • B. 

      K versus (1/T)

    • C. 

      Ln k versus (1/T)

    • D. 

      Ln k versus T

  • 14. 
    Which of the following would DECREASE the rate of a chemical reaction?
    • A. 

      Decreasing the activation energy.

    • B. 

      Increasing the concentrations of the reactants.

    • C. 

      Increasing the temperature.

    • D. 

      Adding a catalyst.

    • E. 

      None of these will decrease the rate.

  • 15. 
    What is the half-life for the reaction assuming first-order kinetics if 75% of a reactant decomposes in 60 minutes?
    • A. 

      120 min

    • B. 

      15 min

    • C. 

      90 min

    • D. 

      30 min

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