Question

lesson 2 review

use vocabulary
1 define description and explanation in your own words.
2 use the term international system of units (si) in a sentence.

understand key concepts
3 which tool would a scientist use to view a tiny organism?
a. computer
b. compound microscope
c. test tube
d. triple - beam balance
4 describe the difference between accuracy and precision.
5 explain why scientists use significant digits.

interpret graphics
6 draw a graphic organizer like the one below. write the name of an si base unit in each circle. add additional circles to the graphic organizer as needed. (image of a graphic organizer with \si base unit\ and three ovals)

critical thinking
7 recommend ways that computers can assist life scientists in their work.

math skills
math practice
8 suppose you measure the mass of a book and it is 420.0890 g. how many significant digits are in this measurement?

Explanation:

Question 8 Solution:

Step1: Recall significant figures rules

Significant figures rules: Non - zero digits are significant. Zeros between non - zero digits are significant. Trailing zeros in a decimal number are significant. Leading zeros are not significant.
For the number \(420.0890\) g:

• The non - zero digits \(4\), \(2\), \(8\), \(9\) are significant.
• The zero between \(2\) and \(0\) (i.e., \(42\boldsymbol{0}.0890\)) is significant (zero between non - zeros).
• The zero between \(0\) and \(8\) (i.e., \(420.\boldsymbol{0}890\)) is significant (zero between non - zeros).
• The trailing zero (the last \(0\) in \(420.089\boldsymbol{0}\)) is significant because it is in a decimal number.

Step2: Count the significant figures

Let's count each significant digit:

• \(4\) (1st)
• \(2\) (2nd)
• \(0\) (3rd, between \(2\) and \(0\))
• \(0\) (4th, between \(0\) and \(8\))
• \(8\) (5th)
• \(9\) (6th)
• \(0\) (7th, trailing zero in decimal)

Answer:

The number of significant digits in the measurement \(420.0890\) g is \(7\).