The answer is letter A definitively .
Answer:
5 moles of electrons
Explanation:
The balance equation is as follow,
<span> 5 Ag</span>⁺ + Mn⁺²<span> + 4 H</span>₂O →<span> 5 Ag + MnO</span>₄⁻<span> + 8 H</span>⁺
Reduction of Ag:
Ag⁺ + 1 e⁻ → Ag
Or,
5 Ag⁺ + 5 e⁻ → 5 Ag
Oxidation of Mn:
Mn⁺² → MnO₄⁻ + 5 e⁻
Result:
Hence 5 moles of Ag⁺ accepts 5 electrons from 1 mole of Mn⁺².
Answer: The kilograms of water must evaporate from 8kg of a 25% salt solution to produce 40% salt solution is 3 kg.
Explanation:
According to the ratio and proportion:

where,
= concentration of ist solution = 25%
= mass of ist solution = 8 kg
= concentration of second solution = 40%
= mass of second solution = ? kg


Thus the final solution must have a mass of 5 kg , i.e (8-5)= 3 kg of mass must be evaporated.
Therefore, the mass that must be evaporated from 8kg of a 25% salt solution to produce 40% salt solution is 3 kg.
The various atomic masses of the same element are called<u> isotopes</u>. They have the same number of protons but different number of neutrons.