A pure substance refers to an element or a compound that has no component of another compound or element. Pure substances are made of only one type of atom or molecule. Hydrogen gas and pure iron are examples of pure substances. Hydrogen consists of hydrogen atoms only while iron consists of only iron atoms. Mixing two pure substances results in a mixture. To separate the two, scientists use a method known as filtration. Mixtures can either be homogeneous or heterogeneous. The measure used to determine how pure a substance may be called purity. Besides hydrogen and iron, other pure substances include gold, diamonds, sugar, and baking soda.
Answer:

Explanation:
1. Mass of zinc
The density of zinc is 7.14 g/cm³
D = m/V

2. Volume of aluminium
The density of aluminium is 2.60/cm³.

Answer:
The object placed in the water has a volume of 19 cm³
Explanation:
<u>Step 1: </u>Data given
volume of the cylinder before adding the object = 28 mL = 28 cm³
After adding an object with volume X the volume rises to 47 mL = 47 cm³
<u>Step 2:</u> Calculate the volume of the object
Volume of the object = Final volume - initial volume
Volume of the object = 47 cm³ (or 47 mL) - 28 cm³ ( or 28 mL) = 19 cm³ (or 19 mL)
The object placed in the water has a volume of 19 cm³
Question 1 is true because it was called Pangea
Question 2 is false because it had a lot of impact on the distribution of species, before the moving continents animals could roam where ever they want but after the splitting of the continents the species were stuck in one place because water separated other continents and land species cant swim.
Hey, what's the question asking you to solve for?