8. A. Density is independent of size (an intensive property).
9. B. The highest density is 1786 g/20cm^3, or 89.3 g/cm^3. The least is 512 g/20cm^3, or 25.6 g/cm^3. Therefore, the difference is 89.3 - 25.6, or 63.7 g/cm^3.
10. C. A bottle filled with air weighs less than one filled with marshmallows, because air is less dense than marshmallows.
11. D. The number represents the number of protons in the nucleus of the atom, as well as the atomic number of the element.
12. C. The number represents the atomic mass of the element, which is determined based on the relative abundance of each form of the element.
The final temperature = 36 °C
<h3>Further explanation</h3>
The balanced combustion reaction for C₆H₆
2C₆H₆(l)+15O₂(g)⇒ 12CO₂(g)+6H₂O(l) +6542 kJ
MW C₆H₆ : 78.11 g/mol
mol C₆H₆ :

Heat released for 2 mol C₆H₆ =6542 kJ, so for 1 mol

Heat transferred to water :
Q=m.c.ΔT

beryllium, magnesium, strontium,barium<span>, and </span><span>radium. </span>
Answer:
Metal
Element: Calcium
Valency: 2
Explanation:
To find the element, let's use the periodic table. (Look below)
We already went past 3 shells, just need the 2 electrons after it.
Just skip to the 4th row and count 2 to the right
We end up at Calcium.
Calcium is a metal and we're also on the alkaline earth metals column.
Calcium will need to lose 2 electrons to reach stability, so the valency is 2.