Answer:
A. 4 only
Explanation:
One of the tests for purity is by determining the melting point of a substance. A pure substance has a sharp meting point.
If the solid in question is a pure solid, when it is heated, it will exhibit a sharp melting point. Mixtures however melt over a range of temperatures due to the presence of impurities in the solid.
A. Is fruit ripening dependent on the type of light the fruit is exposed to, because B, C, and D are all based on opinion and different mind sets whereas A can be found out through experimentation.
Answer:
A. When two boundary plates are moving slowly toward each other.
When you drop iodine on a leaf you may observe a colour change of orange/brown to a blue/black complex.
This is because in the leaf there are starch molecules that form a blue/black complex with the starch molecules.
hope that helps :)
