Which is an example of a chemical change that occurs during weathering? A. freezing and thawing of water in the cracks of rocks
B. Animals dig a hole in the ground looking for worms
C. flowing water smooths rock surfaces in a river
D. Acids from the lichens growing on the rock breaks down the rock to soil

Kelly ran electricity though a sample of water using electrolysis. the water changed into two gases, x and y. it was not possible to break down the gases x and y into simpler particles.

What can be said about farmers in highly developed countries? a) they have little or no negative impact on the environment. b) they practice subsistence agriculture. c) they are able to incorporate polyculture into their farming practices. d) they utilize organic farming techniques on a regular basis. e) they rely on large amounts of energy from fossil fuels.

Four different thermometers were used to measure the temperature of a sample of pure boiling water. the measurements are recorded in the table below. thermometer temperature reading 1 temperature reading 2 temperature reading 3 w 100.1°c 99.9°c 96.9°c x 100.4°c 102.3°c 101.4°c y 90.0°c 95.2°c 98.6°c z 90.8°c 90.6°c 90.7°c the actual boiling point of pure water is 100.0°c. what can be concluded from the data about the reliability and validity of the thermometers?