1. Here’s a list of SI prefixes worth knowing:
QUESTION:
Which of the following is not equivalent to 10-3 mg? A g, B. 1 g, C cg, D. 106 ng
Here’s a list of SI prefixes worth knowing:
d = deci = 10-1, c = centi = 10-2, m = milli = 10-3,
 = micro = 10-6, n = nano = 10-9, p = pico = 10-12
k = kilo = 103, G = giga = 109
Express all quantities in grams:
10-3 mg = 10-3 x 10-3 g, or 10-6 g
1 g = 10-6 g
10-4 cg = 10-4 x 10-2 g, or 10-6 g
106 ng = 106 x 10-9 g, or 10-3 g
SCRIPT 1A-1-2
Which of the following is not equivalent to ten to the negative third milligrams?
Ten to the negative sixth grams…
One microgram…
Ten to the negative fourth centigram… Or
Ten to the sixth nanograms
To answer this question, you need to be familiar with SI prefixes. Here’s a list that you really should know by heart.
CLICK
A good strategy for answering this type of question is to express everything in terms of the unprefixed unit. In this case, let’s express everything in terms of grams.
The prefix milli means ten to the negative third. Therefore, ten to the negative third milligrams is equal to
Ten to the negative third times ten to the negative third grams, or ten to the negative sixth grams. Remember that when multiplying powers of ten, we simply add up the exponents.
The prefix micro, represented by the greek letter mu, means one one-millionth, or ten to the negative sixth. Therefore, one microgram is equal to ten to the negative sixth grams.
CLICK The prefix centi means one one-hundredth, or 10 to the negative two. Therefore, 10 to the negative 4th centigram is equal to 10 to the negative fourth times to ten the negative two, or ten to the negative sixth grams.
Finally, the prefix nano means one one-billionth, or ten to the negative ninth. So, ten to the sixth nanograms is equivalent to ten to the negative third grams.
Let’s see…
ten to the negative third milligrams, and the first three choices are all equal to ten to the negative sixth grams.
Therefore the correct answer is ten to the sixth nanograms. It’s equal to one milligram. All the other choices are equal to one microgram.

2. Video ID: 1A-1-2 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08