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 c. test tube
b. compound d. triple - beam
microscope 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 si base unit graphic
critical thinking
7 recommend ways that computers can assist life scientists in their work.
math skills
8 suppose you measure the mass of a book and it is 420.0800 g. how many significant digits are in this measurement?

Explanation:

Question 3

To determine the tool for viewing a tiny organism, we analyze each option:

• A. Computer: Used for data processing, not viewing tiny organisms.
• B. Compound microscope: Designed to magnify small objects/organisms for observation.
• C. Test tube: Used for holding substances, not viewing.
• D. Triple - beam balance: Measures mass, not for viewing organisms.

So the correct tool is the compound microscope.

Step 1: Recall significant digit rules

Significant digits include: all non - zero digits, zeros between non - zero digits, and trailing zeros in a decimal number.

Step 2: Analyze the number 420.0800 g

• Non - zero digits: 4, 2, 8 (3 digits).
• Zero between non - zero digits: the zero between 2 and 0 (after the decimal) and the zero between 0 and 8 (1 digit).
• Trailing zeros in decimal: the two zeros at the end (2 digits).
• Now sum them up: 3+1 + 2=6? Wait, let's do it step by step. The number is 420.0800.
• 4 is significant, 2 is significant, 0 (between 2 and 0 after decimal) is significant, 0 (between 0 and 8) is significant? Wait no, the number is 420.0800. Let's write it as 4.200800×10².
• Non - zero digits: 4,2,8 (3).
• Zeros between non - zero digits: the zero between 2 and 0 (after decimal) and the zero between 0 and 8? Wait, no, the digits are 4,2,0,.,0,8,0,0.
• Rules:
• All non - zero digits (4,2,8) are significant.
• Zeros between non - zero digits: the 0 between 2 and 0 (after decimal) and the 0 between 0 and 8? Wait, no, the number is 420.0800. Let's count:
• 4: significant.
• 2: significant.
• 0: between 2 and 0 (after decimal) – significant (because it's between non - zero digits? Wait, 420.0800: the first 0 is after 2 and before the decimal? No, 420.0800 is 4 (hundreds), 2 (tens), 0 (units), decimal, 0 (tenths), 8 (hundredths), 0 (thousandths), 0 (ten - thousandths).
• Non - zero digits: 4,2,8 (3).
• Zeros between non - zero digits: the 0 between 2 and 0 (units place) – no, that's a trailing zero before decimal? Wait, no, the rule for trailing zeros before decimal: only significant if there's a decimal. Wait, 420.0800: the 0 after 2 (in 420) – since there's a decimal after, that 0 is significant? Wait, no, 420.0800: let's use the rules properly.
• Rule 1: All non - zero digits are significant. So 4,2,8 are significant (3 digits).
• Rule 2: Zeros between non - zero digits are significant. Here, the 0 between 2 and 0 (after decimal) – wait, 420.0800: digits are 4,2,0,.,0,8,0,0. So between 2 and 0 (before decimal) – no, that's a trailing zero in a whole number part? Wait, no, the number is 420.0800, which is a decimal number. So:
• The 0 after the decimal (tenths place): significant because it's between non - zero digits? Wait, 420.0800: 4 (1), 2 (2), 0 (3) [the zero in the units place, but since there's a decimal, this zero is significant? Wait, no, the correct way:
• For the number 420.0800:
• Digits: 4,2,0,0,8,0,0 (after decimal). Wait, no, 420.0800 is 4 hundreds, 2 tens, 0 ones, 0 tenths, 8 hundredths, 0 thousandths, 0 ten - thousandths.
• Significant digits:
• 4: significant.
• 2: significant.
• 0 (ones place): significant because it's between 2 (ten) and 0 (tenths) and there's a decimal.
• 0 (tenths place): significant (between 0 (ones) and 8 (hundredths)).
• 8 (hundredths place): significant.
• 0 (thousandths place): significant (trailing zero in decimal).
• 0 (ten - thousandths place): significant (trailing zero in decimal).
• Now count: 4,2,0,0,8,0,0 – wait, no, that's 7? Wait, no, let's do it again. The number is 420.0800.
• Non - zero: 4,2,8 (3).
• Zeros between non - zero: the 0 between 2 and 0 (after decimal) – no, 420.0800: 4 (1), 2 (2), 0 (3) (the zero in the ones place, because the decimal is present, so this zero is significant), 0 (4) (tenths place, between 0 (ones) and 8 (hundredths)), 8…

Answer:

B. compound microscope

Question 8