Answer:
[tex]\boxed {\boxed {\sf 2 \ significant \ figures}}[/tex]
Step-by-step explanation:
According to the "rules" of significant figures, all the zeroes to the right of the final non-zero number are not significant, unless there is a decimal point.
We are given the measurement:
84,000 kg
If there was a decimal point (84,000.0 kg), then there would be 5 significant figures.
Since there isn't a decimal point, all 3 zeroes to the right of the number 4 aren't significant. The 8 and 4 are significant, so there are 2 significant figures.
