Basically, the graph shows a linear (line) relationship with mass and volume. The slope will equal the density of the substance because mass/volume is the equation for density. Your paper is a bit unclear, but I can understand this much, Hope this helped a little bit :)
Answer:
nitrogen in atmospheres of a sample is 0.679
Signs that a chemical reaction is occurring are: 1. change in color 2. change in odor 3. change in pH, as in changes from acid to base or base to acid
Answer:
The order of reactivity of metals is as follows, Potassium > Sodium > Lithium > Calcium > Magnesium > Aluminium > Zinc > Iron > Copper > Silver > Gold.
Explanation:
The reactivity of elements (metals) towards water decreases towards the right in a period. It also increases down the group. But zinc is more reactive towards water than iron. Hence the correct order is:
Iron<Zinc<Magnesium<Sodium
The metric system is based on powers of 10 so it is much easier to convert units, often just by moving the decimal point.