Answer: Bohr postulated that electronic energy levels are quantized. Secondly, a photon of light of a particular frequency is emitted when electrons move from a higher to a lower energy levels.
Explanation:
The Bohr model of the atom is the immediate predecessor of the wave mechanical model of the atom. The wave mechanical model refined the Bohr's model by treating the electron as a wave having a wave function psi. The wave function describes the identity of the electron. From Heisenberg uncertainty principle, the position of a particle cannot be accurately and precisely measured. Hence the wave mechanical model added that electrons are not localized in orbits according to Bohr's model but the integral of psi squared dx gives the probability of finding the electron within a given space.
<span>Answer: B. Ionic solids have higher melting points than molecular solids.
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This is because the rest are false, as solids are able to melt, and do have melting points. Also, not all solids have the same melting points.
Answer: 9.68 x 10^10 grams.
Explanation:
Given that:
Mass of CO2 = ?
Number of molecules of CO2 = 2.2x10^9 molecules
Molar mass of CO2 = ? (let unknown value be Z)
For the molar mass of CO2: Atomic mass of Carbon = 12; Oxygen = 16
= 12 + (16 x 2)
= 12 + 32 = 44g/mol
Apply the formula:
Number of molecules = (Mass of CO2 in grams/Molar mass)
2.2x10^9 molecules = Z/44g/mol
Z = 2.2x10^9 molecules x 44g/mol
Z = 9.68 x 10^10g
Thus, the mass of 2.2x10^9 molecules of CO2 is 9.68 x 10^10 grams.
2H2O+O2--->2H2O2
8.5 gm H2O2=0.25 mole
hence H2O is also 0.25 mole i.e.4.5 gm
O2is 0.125 mole i.e.4 gm
