Lab operations - BOC (Copy)
How many mL of rbc's are to be used to make 25 mL of a 4% red cell suspension? a. .25 mL b. .5 mL c. 1 mL d. 2 mL
C The most commonly used equation for preparing suspension solution is V1 X C1 = V2 X C2. A 4% red cell suspension contains 4 mL of red cells per 100 mLs. Therefore (25) x (4) = 100 x (x)
Many laboratory procedures are conducted at 37o C. This corresponds to what temperature on the Fahrenheit scale: The correct answer is highlighted below 4.0° F 25.0° F 72.0° F 98.6° F
To convert Fahrenheit to Celsius, subtract 32, then multiply by 0.555. To convert Celsius to Fahrenheit, first multiply by 1.8, and then add 32.
which of the following is the formula for calculating the dilution of a solution? a. V1 + C1 = V2 + C2 b. V1 + C2 = V2+ C1 c. V1 X C1 = V2 X C2 D. V1 X V2 = V1 X C2
C
The volume of 25 % stock sulfosalicylic acid needed to prepare 100 mL of 5% working solution is: a. 1.25 mL b. 5 mL c. 20 mL d. 50 mL
C The most commonly used equation for preparing suspension solution is V1 X C1 = V2 X C2. In this case (100) (5) = (x) x (25)
Chromatography is based on the principle of: a. differential solubility b. gravity c. vapor pressure d. temperature
A
Nephelometers measure light: a. scatter at a right angle to the light path b. absorbed suspended particles c. transmitted by now particle mixtures d. reflected back to the source form opaque suspensions
A
The nanometer is the measurement of: a. wavelength of radiant energy b. specific gravity c. density d. intensity of light
A
Which of the following is the formula for calculating a percent (w/v) solution? a. gams of solute/volume of solvent x 100 b. gram of solute x volume of solvent x 100 c. volume of solvent/ grams of solute x 100 d. (grams of solute x volume of solvent)/100
A
A solutions contains 20 grams of solute dissolved in .5 L of water. What is the percentage of this solution? a. 2% b. 4% c. 6% d. 8%
B
How many grams of sulfosalicylic acid (MW = 254) are required to prepare 1 L of a 3 % (w/v) solution? a. 3 b. 30 c. 254 d. 300
B
In sptrophotometry, the device that allows for a narrow band of wavelength is the: a. hollow cathode lam b. monochromator c. refractometer d. photodetector
B
The double beam photometer, the additional beam is used to: a. compensate for variation in wavelength b. correct for varation in light source intensity c. correct for changes in light path d. compensate for variation in slit widths
B
The reliability of a test to be positive in the presence of disease it was designed to detect is known as: a. accuracy b. sensitivity c. precision d. specificity
B
What is the molarity of H2SO4 (GMW = 98) that has a specific gravity of 1.21 and an assay weight of 68% w/v? The correct answer is highlighted below 0.84 M 8.4 M 1.68 M 16.8 M 0.168 M
B
Which of the following is the formula for standard deviation? a. square root of the mean b. square root of (sum of squared differences)/(N-1) c. square root of the variance d. square root of (mean)/(sum of squared differences)
B
Mass spectrometer detects which property of ionized molecultes? a. column retention time b. charge to mass ratio c. mass to charge ratio d. flourescence
C
Which of the following parameters of a diagnostic test will vary with the prevalence of a given disease in a population? a. precision b. sensitivity c. accuracy d. specificity
C
One means of checking a spectrophotometer wavelength calibration in the visible range is by using a: a. quartz filter b. diffraction grating c. quartz prism d. didymium filter
D
When .25 mL is diluted into 20 mL, the resulting dilution is: a. 1:20 b. 1 :40 c. 1 :60 d. 1:80
D
What is the molarity of an unknown HCl solution that has a specific gravity of 1.10 and an assay percentage of 18.5%? (Atomic weight: HCl = 36.5) The correct answer is highlighted below 5.6 mol/L 6.0 mol/L 6.3 mol/L 6.6 mol/L 5.0 mol/L
Molarity = (Specific Gravity x % assay weight x 10) / (gram molecular weight) Molarity = (1.1 x 18.5 x 10) / 36.5 = 5.6 mol/L
General Hospital is considering the addition of a new chemistry panel containing 12 tests. The laboratory is asked to calculate the total cost of quality control per new chemistry test panel. Quality control must be performed 3 times per day (every 8 hours). The labor cost per quality control test for this panel is $2.63. A month's worth of quality control reagent costs $354.00. What is the total quality control cost per new chemistry test panel if 76,000 of these new panels are performed each year? The correct answer is highlighted below $0.01 $0.09 $0.04 $1.70
This scenario's answer can be calculated by first deciding what the total quality control labor costs are as well as what the total consumable costs are. In this case, if quality control is run 3 times per day, a total of 1095 quality control runs are performed each year. The direct labor cost of $2.63 multiplied by 1095 quality control runs equals $2879.85 per year in quality control direct labor. The hospital pays $354.00 per month on quality control consumables, which equals $4248.00 per year. The total quality control costs in a year are equal to $2879.85 + $4248.00 = $7127.85. If 76,000 new chemistry tests panels are peformed each year, the total quality control cost per new chemistry test panel will be $0.09.
How many milliliters of a 5 M solution would be needed to make 250 ml. of a 2 M solution? The correct answer is highlighted below 20 ml 40 ml 62.5 ml 100 ml 625 ml
To solve: (V1)(M1) = (V2)(M2) Where V = volume and M = molarity (V1)(5M) = (250 mL)(2M) 5V1 = 500 mL V1 = 100 mL (or 100 mL 5M solution) Therefore, when 100 mL of a 5M solution is diluted to 250 mL, the resultion soltution is 2M.
