Answer: -
Magnesium reacts very slowly to form magnesium hydroxide and hydrogen gas. The balanced chemical equation for the reaction is
Mg + 2H₂O → Mg(OH)₂ + H₂
Explanation: -
Chemical symbol of magnesium = Mg
Chemical formula for magnesium hydroxide = Mg(OH)₂
Chemical formula for hydrogen gas = H₂
The other reactant with Mg must be water H₂O.
Thus the balanced chemical equation for the reaction is
Mg + 2H₂O → Mg(OH)₂ + H₂
Answer : Option A) Sodium
Explanation : Sodium is the element which is most reactive tin the given options.
Sodium has the atomic number as 11, which is distributed in the atomic shells as 2-8-1.
So, it is clear that the outermost valence shell contains only one electron in sodium. To give away one electron and attain the octet state is easy for sodium. If it donates the electron it becomes a cation which is very reactive, as it gets a positive charge on itself.
Compared to the valency of the other atoms given here, Nickel has 2 valence electrons so it will be less reactive than Sodium.
Carbon has 4 valence electrons which is less than sodium and oxygen needs 2 electrons to be an octet which is also less.
Answer:
One distinguishing feature between physical and chemical changes is that a physical change can be reverse or turn back to its original form, but chemical change cannot be return to its form because the material change.
Explanation: