Answer : Option A) Atomic number of Arsenic is 33.
Explanation : Arsenic contains same number of protons in its atomic nucleus. In arsenic there are 33 protons found in the atomic nucleus. Hence, the atomic number will be 33. It has 5 valence electrons in its outermost shell, which is also called as valence shell. So, its valency becomes 5.
Answer:

Explanation:
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In this case, the enthalpy of combustion is understood as the energy released when one mole of fuel, in this case octene, is burned in the presence of oxygen and is computed with the enthalpies of formation of the fuel, carbon dioxide and water as shown below (oxygen is circumvented as it is a pure element):

Thus, since we already know the enthalpy of combustion of the fuel, for carbon and water we have -393.5 and -241.8 kJ/mol respectively, thereby, the enthalpy of combustion turns out:

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Distance and period of time
Answer:
Option 1, Cl is reduced and gains electrons
Explanation:
HClO₃ → HClO₂
In HClO₃, chlorine acts with +5 in the oxidation state
In HClO₂,, chlorine acts with +3 in the oxidation state.
The state has been reducted, so the Cl has been reduced. As it was reduced, it means that has won e⁻, in this case 2
Cl⁻⁵ → Cl⁻³ + 2e⁻
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