2. Practice: Look at the quantities mentioned in the Metric units only Distance problems. For each value, state the number of significant digits in the first column and the rule(s) you used
to determine the number of significant digits. The first has been done for you.
Question
Number of
significant digits
Rule(s) used
I
3
1.4
The tallest building in the world, the Burj Khalifa in
Dubai, is 0.828 kilometers high.
The largest human cell is the egg cell, with a
diameter of 121 micrometers.
On a caterpillar's map, all distances are marked
in millimeters. The caterpillar's map shows that
the distance between two milkweed plants is
4,012 millimeters.
The closest star to our Sun is Proxima Centauri,
which is 4.242 light years away.
A helium atom has a diameter of 9.8. 10°
meters.

The earth's moon is unusually large. two popular theories of the moon's origin include the "sister world" hypothesis, which states that the moon formed from the same materials as the earth, near enough to the earth that they fell into orbit around each other. a second theory is the "capture" hypothesis, in which the moon formed elsewhere in the solar system, and the earth's gravity pulled it into its orbit. studies of what the moon is made of indicate that some of its materials had to come from the earth or from the same area of the solar system where the earth had formed. at the same time, the moon does not contain much of the material that makes up the earth's core, so the moon could not have formed from the same materials as the earth. how do the two facts above affect the described theories of the moon's origin? a. they show that scientists will never agree on where the moon came from. b. they show that more experiments on moon formation need to be done. c. they show that no theory accounts for the existence of the moon. d. they show that neither theory is complete and entirely correct.

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? a. the balloons both rise. the cold balloon is larger than the warm balloon. b. the balloons rise at the same rate. both balloons are the same size. c. the warm balloon expands and rises. the cold balloon shrinks and sinks. d. the cold balloon expands and rises. the warm balloon shrinks and sinks.

What is the empirical formula of c6h18o3? ch3o c2h5o c2h6o c2h5o5