Question

Jeff used an equal arm balance to weigh a 4.312 g sample of sodium chloride. Which of these measurements made by Jeff is the most accurate?4.1 g4.2g4.3g 4.5 g

Answer 1

Answer:

4.3g

Explanation:

Accuracy measures how close a measured is to the expected value., For example if the given density of a metal is 0.78 g/ml and the measured densities are 0.67 g/ml and 0.77 g/ml, the later measured value of density is more accurate than the former value.  

4.3 g measured by Jeff is closest to the expected value of 4.312 g.

Answer 2

Option B: 4.3

There are following rules for rounding off numbers:

1. If the rounding digit has digit less than 5 (1,2,3 and 4) to its right, all the digits on right side of the rounding digit will drop out.

2. If the rounding digit has digit equal and greater than 5 (5,6,7,8 and 9) to its right, one is added to the rounding digit.

Jeff has to weigh 4.312 g sample of NaCl. To round off the underline number 4.312, check for the digit right to it. It has 1, which is less than 5 thus according to the Rule 1, all the digits on right side of the rounding digit will drop out and the number gets rounded off to 4.3.

Therefore, 4.3 is most accurate measurement by Jeff.