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

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.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.