[xneurocentric]

Hi, everyone. 

First time poster here; hoping to get acquainted well with the site, as I see myself having A LOT of questions!

I'm working on a practice exam for my first Gen Chem exam next week, and one of the questions has me stumped. It says:

Which of the following is heaviest (that is, largest in mass)?

A) 3.0kg
B) 3000.cg
C) 3.0 x 10^-12Gg
D) 3.0 x 10^10ng
E) 3.0 x 10^6μg

The answer given on the sheet is A.

I really have no clue how to go about solving this problem. Are we looking at sig figs, dimensional analysis, conversions..? I'm confused, so any advice will be helpful. Thanks!

[Arkcon]

OK, you have a number of measurements:  there are abbreviations of the metric prefixes, and some exponential notation.  Can you convert them all into one unit?  The best was would be to express them all in scientific notation -- that is: 3.00  then whatever exponent is needed to give the correct value.  Oh, and use the appropriate SI unit, which is the gram -- g, without prefixes.

[xneurocentric]

OK, you have a number of measurements:  there are abbreviations of the metric prefixes, and some exponential notation.  Can you convert them all into one unit?  The best was would be to express them all in scientific notation -- that is: 3.00  then whatever exponent is needed to give the correct value.  Oh, and use the appropriate SI unit, which is the gram -- g, without prefixes.

Thanks for your response, but I'm not sure what you're telling me to do, really. Is that how I solve the problem? When you ask me "Can you convert them all into one unit?" do you mean each answer themselves, or was this a general question?

[Arkcon]

Yes, for this one.  For example, 3.0 kilograms is 3.0 X 10^? grams?  3000 centigrams is 3.000 X 10^? grams?  Once you've answered that, you'll never get one of these types of questions wrong.  They will always work something like this into later more complicated problems, so you'll want to get used to it.  (Notice:  I'm giving away the significant figures for you.)

[xneurocentric]

Yes, for this one.  For example, 3.0 kilograms is 3.0 X 10^? grams?  3000 centigrams is 3.000 X 10^? grams?  Once you've answered that, you'll never get one of these types of questions wrong.  They will always work something like this into later more complicated problems, so you'll want to get used to it.  (Notice:  I'm giving away the significant figures for you.)

Okay, I get it now, definitely! Thanks so much!