<u>Answer 1 :</u> The synthesis reaction is,
Explanation :
Synthesis reaction : It is a type of reaction in which the reactants present in elemental state react to give a single product.
(1)
This is a synthesis reaction.
(2)
This is a single displacement reaction in which the most reactive element displaces the least reactive element.
(3)
This is a decomposition reaction in which larger reactant decomposes to give two or more products.
(4)
This is a neutralization reaction in which an acid and a base react to give a salt and water as a product.
<u>Answer 2 : </u>The number of half-lives it take will be, 3
Formula used :
where,
a = amount of reactant left after n-half lives =
= Initial amount of the reactant
n = number of half lives
Putting values in above equation, we get:
n = 3
Therefore, the number of half-lives it take will be, 3