1. A mole of atoms contains exactly 6.02x1023 atoms.
QUESTION:
Which of these is false?
A mole of atoms contains exactly 6.02x1023 atoms.
B. The exact number of molecules in one mole of molecules is equal to Avogadro's number.
C. The exact number of ions in one mole of ions is equal to Avogadro's number.
D. None of the above
Avogadro’s number is a 24-digit number:
602, (about 602 billion trillion)
To three significant digits, it is approximately 6.02x1023
Avogadro’s number is equal to the number of atoms present in exactly 12 grams of Carbon-12.
Which of these is false?
A. A mole of atoms contains exactly 6.02x1023 atoms.
B. The exact number of molecules in one mole of molecules is equal to Avogadro's number.
C. The exact number of ions in one mole of ions is equal to Avogadro's number.
D. None of the above
PAUSE CLICK
A mole is a way of counting, just like a dozen. While a dozen count is exactly equal to twelve,
a mole count is exactly equal to Avogadro’s number
So choices B and C are true.
HIGHLIGHT “exact” and “Avogadro’s number” in choices B and C.
Choice A is not true because Avogadros’ number is not exactly 6.02x1023
CROSS OUT “exactly” in choice A
CLICK Avogadro’s number is a 24-digit exact number. Unfortunately, we do not yet know all 24 digits. The first six digits are known to be and 3...
These are followed by 18 more digits.
CLICK To three significant digits, it is approximately equal to 6.02x1023.
That’s about 602 billion trillion.
Since we’re being asked for the False statement, the correct answer is choice A.
By the way, the exact definition of a mole count or Avogadro’s number is this...
It’s equal to the number of atoms present in exactly 12 grams of Carbon-12.
Imagine you have a sample that is exactly 12 grams, and each and every atom in the sample is carbon-12.
Then, if you could get an exact count of all the atoms in that sample, the number you get is defined
as Avogadro’s number.
CLICK PAUSE END RECORDING

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