Answer:
c. Only certain energies are allowed for the electron in a hydrogen atom
Explanation:
Emission spectrum are produced when the excited electron in a atom release the energy in the form of photons to come to ground state. These photons are of different wavelengths depending on the excitation state of emitting electron or transition of electron. These electromagnetic radiation are observed through prism to produce the spectrum.
As the name indicates this spectrum is produced by emission of energy. Although the electron can be excited by different methods such as by heating but the key point is that electrons in hydrogen atom will emit the photons of same energy which they absorb and each electron can absorb only certain type of energy. So four lines were observed in the visible spectrum of hydrogen because only certain energies are observed for hydrogen atom.
Answer : The change in energy of an atom is, 
Solution : Given,
Wavelength of the photon = 
Formula used :
where,
E = energy of an atom
h = Planck’s constant = 
c = speed of light = 
= wavelength of photon
Now put all the given values in the above formula, we get the energy of an atom.
Therefore, the change in energy of an atom is,
Answer:
H₂O
Explanation:
Chemical equation:
C₅H₁₂ + O₂ → CO₂ + H₂O
Balanced chemical equation:
C₅H₁₂ + 8O₂ → 5CO₂ + 6H₂O
The given reaction is combustion reaction. The balance equation shows that there are equal number of moles of carbon, hydrogen and oxygen on both side of equation thus it follows the law of conservation of mass.
Combustion reaction:
The reaction in which substance react with oxygen and produced carbon dioxide and water.
Mostly hydrocarbons burns in the presence of oxygen and form carbon dioxide and water.
CaO ( calcium oxide) is a basic oxide.
