TLS Online TPP Program

#Question id: 12570


Extinction is a natural phenomenon. It is estimated that 99% of all species that ever lived are now extinct. Why then do we say that we are now in a biodiversity crisis?

#Unit 10. Ecological Principles
  1. Humans are ethically responsible for protecting endangered species.
  2. Scientists have finally identified most of the species on earth and are thus able to Quantify the number of species becoming extinct.
  3. The current rate of extinction is high and human activities threaten biodiversity at all levels.
  4. Humans  have  greater  medical  needs  than  at  any  other  time  in  history,  and  many  potential  medicinal compounds are being lost as plant species become extinct.
More Questions
TLS Online TPP Program

#Question id: 379

#Unit 1. Molecules and their Interaction Relevant to Biology

A compound has a pKa of 7.4. To 100 mL of a 1.0 M solution of this compound at pH 8.0 is added 30 mL of 1.0 M hydrochloric acid. The resulting solution is pH:

TLS Online TPP Program

#Question id: 380

#Unit 1. Molecules and their Interaction Relevant to Biology

The Henderson-Hasselbalch equation:

TLS Online TPP Program

#Question id: 381

#Unit 1. Molecules and their Interaction Relevant to Biology

Consider an acetate buffer, initially at the same pH as its pKa (4.76). When sodium hydroxide (NaOH) is mixed with this buffer, the:

TLS Online TPP Program

#Question id: 382

#Unit 1. Molecules and their Interaction Relevant to Biology

The molar ratio of sodium acetate to acetic acid in a buffer solution with a pH OF 5.76 is 10:1. Assuming the total buffer concentration is 2.2 X 10-2 mol/L, how many grams of sodium acetate (m.w. 82) and how many grams of acetic acid (m.w. 60) should be used in preparing a litre of the solution?

TLS Online TPP Program

#Question id: 383

#Unit 1. Molecules and their Interaction Relevant to Biology

Three buffers are made by combining a 1 M solution of acetic acid with a 1 M solution of sodium acetate in the ratios shown below

1 M acetic acid              

1 M sodium acetate  

Buffer 1: 10 mL

 90 mL

Buffer 2: 50 mL

50 mL

Buffer 3: 90 mL

10 mL

 Which of these statements is true of the resulting buffers?

TLS Online TPP Program

#Question id: 384

#Unit 1. Molecules and their Interaction Relevant to Biology

A solution was prepared by dissolving 0.02 moles of acetic acid (HOAc; pKa = 4.8) in water to give 1 liter of solution. What is the pH? To this solution was then added 0.008 moles of concentrated sodium hydroxide (NaOH). What is the new pH? (In this problem, you may ignore changes in volume due to the addition of NaOH).