Which of the following is a chemical reaction?

1-Painting a wall blue

2-A bicycle rusting

3-Ice cream melting

4-Making a sand castle

What happens to the copper sulphate crystals when they are heated that causes them to change color?

Which societal problem can be solved, in part, by scientists identifying areas of high biodiversity? A. reducing the amount of pollution B. finding affordable housing C. protecting the environment D. providing access to clean water

Which method would be effective for separating salt and water in a mixture? A. evaporation B. using a magnet C. observing color differences D. chromatography

The water cycle includes the circulation of all of the water on Earth. Which of these would be included in the water cycle?

What is the relationship between variable x and variable y? As variable x increases, variable y increases. As variable x increases, variable y decreases. Both variables show a trend toward decreasing values.

What are the first five elementsof the periodic table?

Name 3 characteristics that can be used to identify minerals

Hemoglobin, the oxygen-carrying protein in red blood cells, has four iron atoms per molecules ad contains 0.340 percent iron by mass. calculate the molar mass of hemoglobin

Nancy wants to find out how the steepness of a hill's slope affects the amount of soil that erodes from it. She has soil, a long pan, and a pile of books with which to build a model hillside. She has a watering can to model rainfall.

Elements on the periodic table are arranged by increasing?