Oxygen in oxides has oxidation number -2.
<span>Al⁺³₂O⁻²₃
+3*2 -2*3=0</span>
During a scientific study a hypotheses is generally modified or discarded
so for first blank the answer is hypotheses
Now in case of phlogiston theory it was assumed that when a substance catches fire it evolve certain substances known as phlogiston which was later on discarded as there is no such particle. Infact a substane undergoing oxidation may gain weight
Hence in second blank the answer is new evidence didn’t support it,
Answer:
7.0 g/mL.
Explanation:
- Density is a characteristic property of a substance.
- The density of a substance is the relationship between the mass of the substance and the volume it takes up.
<em>d = m/V,</em>
where, d is the density of the metal,
m is the mass of the metal (m = 147 g),
V is the volume that the metal takes up (V = 41.0 mL - 20.0 mL = 21.0 mL).
<em>∴ d = m/V</em> = (147 g)/(21.0 mL) =<em> 7.0 g/mL.</em>
Sodium has a mass number of 23amu. Since sodium has 11 protons, the number of neutrons must be 23 – 11 = 12 neutrons.
