Did you know the roller skate has been around since early 1700s? people who loved winter ice-skating wanted to go "dry land skating" in the summer, and so they attached wheels to their boots. the early models were hards to roll, though. in the late 1800s, roller-skate design improved. once the skaters were easier to handle, he sport became more popular.

which of these best states the main idea of the passage?

a) people liked ice-skating in the winter
b) many people wanted to skate in the summer.
c) roller-skating has become a popular sport over time
d) early roller skates were difficult to use

The starting materials in a nuclear change have a total mass of 2.3465 x 10-27 kg. after the change, the resulting materials have a mass of 2.3148 x 10-27 kg. how much energy was released during the change? 2.85 x 10-12 2.08 * 10-10 j 0 211 * 10-10 j 8.56 * 10-43

Imagine you are a student in alfred hershey and martha chase's lab in the late 1940's. you are given five test tubes with the e. coli bacteria that were infected with t2 bacteriophage that have been labeled with 32p or 35s. unfortunately, you forgot to label the tubes and are now uncertain which were 32p labeled and which were 35s labeled. you place the contents of each tube in a blender and pulse it for a few seconds to shear off the protein coats from the bacterial outer membranes. you then centrifuge the contents to seperate the protein coats and the bacterial cells. you then check for radioactivity and obtain the results shown below. which tubes contained e. coli infected with the phage labeled with 32p? select all tubes that apply.

Which of the following substances most likely dissolve in water? check all that apply •paraffin