Whenever any substance goes under chemical change so any of the reaction will happen either both or multiple compounds will combine to produce combination reaction either one compound will decompose itself into 2 or more compounds or elements and last one is replacement reaction the either reaction is not even going to combination nor decomposition, So when a reaction like that happens it must replacement reaction.
Now the question is what's the condition required for it, so basically a chemical reaction when takes place it depends upon several factor on the basis of which we conclude products. The factors are Temperature,catalyst,reagents, either what is the mechanism of reaction, stability of reactants and stability of products and alot more.
During reaction sometimes gas forms and sometimes not yea and well that also depends on the chemical reactivity and stability of product sometimes product found itself most stable releasing the gas evolving so it's been done itself and sometimes we add catalyst and adjust the reaction to extract that gas and get desirable product manually.
I wrote all i know if sorry if this is not what you're looking for :(
Answer:
The following reaction will occur at cathode:

Explanation:
The two half reaction during electrolysis of aqueous nickel sulfate will be
a) anode reaction :
Water will undergo oxidation and will evolve oxygen gas at anode as shown in the given reaction:

b) Cathode reaction: The reduction of Nickel ion will occur by gain of two electrons as shown in the given equation:

Thus the overall reaction will be:

pH. 10 because it is strong base
Answer:
3 is the coefficient of oxygen.
Explanation:
Chemical equation:
CH₃OH + O₂ → CO₂ + H₂O
Balanced chemical equation:
2CH₃OH + 3O₂ → 2CO₂ + 4H₂O
The given reaction is combustion reaction. In this reaction methanol is burn in the presence of oxygen and produces carbon dioxide and water.
The balance equation show reaction also follow the law of conservation of mass.
This law was given by French chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.
Answer:
Metallic bonding is the type of chemical bonding that occurs between atoms of metals. In a metallic bond, atoms share their electrons in a way that allows them to form a “sea” of free electrons. This electron sea is responsible for the unique physical and electrical properties of metals.
Explanation: