Answer:
The last option
Explanation:
The Bohr model was an attempt to explain atomic hydrogen's spectrum. This was done by establishing energy levels of separate electron orbits in the atom.Thos model was followed by the Schrödinger model.
When it passes from one medium
Answer:
If one of the reactants is a solid, only the particles at the surface can partake in the reaction. Breaking the reactant into smaller pieces increases the surface and more particles are exposed to the reaction mixture. This results in an increased frequency of collisions and therefore a faster rate of reaction
38.46g
Explanation:
Given parameters:
Mass of CaF₂ = 75.0g
Unknown:
Mass of calcium that can be recovered = ?
Solution:
This is a mass percentage problem and we need to solve it accordingly.
To solve this problem;
Find the molar mass of CaF₂
Find the ratio between the molar mass of Ca and that of CaF₂
Multiply by the given mass
Molar mass of CaF₂ = 40 + (2 x 19) = 78g/mol
Mass of calcium =
x 75 = 38.46g
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The correct answer is high temperature solids