Revision questions
1. a human hair is about 50 pm thick. a pet flea is about 1 mm in size. how
many times smaller is the thickness of a human hair than a flea?

What is the value of keq for the reaction expressed in scientific notation?

Apiece of metal with a length of 1.42 cm was measured using four different instruments. which of the following measurements is the most accurate?

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.