1. The liquid phase controls the rate of mass transfer for compounds which have an H value of which of the following?
a) H>0.05
b) H=0.02
c) H<0.002
d) H=1
Explanation: The liquid phase controls the rate of mass transfer for compounds which have an H value >0.05. The gas phase controls the rate of mass transfer for compounds which have an H value <0.002. For compounds with H value between 0.002 and 0.05, both liquid and gas control the rate of mass transfer.
2. C= x⁄v
What does x stand for in the above formula?
a) Particles
b) Quantity
c) Volume
d) Area
Explanation: The formula is for the concentration of the liquid sample. C stands for concentration, P stands for particles and V stands for volume. So the actual formula is C=P/V.
3. Dilution=volume added/total volume. What does total volume indicate?
a) Volume of the sample
b) Volume of the sample including blank
c) Volume of the sample excluding blank
d) Volume of the blank
Explanation: Dilution = volume added / total volume
Dilution = volume added / (volume of blank + volume added).
4. Dilution factor is the reciprocal of dilution.
a) True
b) False
Explanation: The total dilution is the product of all dilutions.
Dtotal = D1 * D2 * D3…..
The Dilution Factor (DF) is the reciprocal of the dilution or 1/dilution.
5. _________ is a step-wise and geometric series of dilutions which starts with a small amount of starting material.
a) Simple dilution
b) Serial dilution
c) Continuous dilution
d) Chemical dilution
Explanation: A serial dilution is a step-wise and geometric series of dilutions which starts with a small amount of starting material and amplifies the dilution factor serially by using a diluted material as a source for subsequent dilutions
6.Which of the following is commonly used?
a) Three – fold dilutions
b) Ten – fold dilutions
c) Five – fold dilutions
d) Six – fold dilutions
Explanation: Two-fold and ten-fold serial dilutions are commonly used to titer antibodies or prepare diluted analytes. Serial dilutions are often performed when titering antibodies or when generating amplified dilutions
7. A dilution is a process that increases the concentration of a substance in a solution.
a) True
b) False
Explanation: A dilution in chemistry is a process that reduces the concentration of a substance in a solution. The repeated dilution of a solution to amplify the dilution factor quickly is called serial dilution.
8. Bacteria is diluted in __________
a) Distilled water
b) Water
c) Culture media
d) Solution
Explanation: Many solutions will be diluted in distilled water, but this is not always the case. If we are diluting bacteria or other cells, it is likely to be diluted it in culture media.
9. What is the minimum amount of sample required to perform serial dilution?
a) 1 ml
b) 5 ml
c) 2 ml
d) 2.5 ml
Explanation: The minimum amount needed to perform the serial dilution is 1 mL of undiluted solution. If there is only 1 mL there will not be any remaining undiluted solution. Solution should be thoroughly mixed before proceeding to the next step.
10. ___________ means that a substance can be converted into simpler compounds by biologically mediated reactions.
a) Non-biodegradable
b) Biodegradable
c) Dilution
d) Assimilation
Explanation: Biodegradable means that a substance can be converted into simpler compounds by biologically mediated reactions. The second law of thermodynamics predicts that oxidation of high energy level organics (relative to low energy level CO2) is favoured.