Answer 1 : The synthesis reaction is, [tex]N_2+3H_2\rightarrow 2NH_3[/tex]
Explanation :
Synthesis reaction : It is a type of reaction in which the reactants present in elemental state react to give a single product.
(1) [tex]N_2+3H_2\rightarrow 2NH_3[/tex]
This is a synthesis reaction.
(2) [tex]MgI_2+Br_2\rightarrow MgBr_2+I2[/tex]
This is a single displacement reaction in which the most reactive element displaces the least reactive element.
(3) [tex]KClO_3\rightarrow KCl+O_2[/tex]
This is a decomposition reaction in which larger reactant decomposes to give two or more products.
(4) [tex]HCl+NaOH\rightarrow NaCl+H_2O[/tex]
This is a neutralization reaction in which an acid and a base react to give a salt and water as a product.
Answer 2 : The number of half-lives it take will be, 3
Formula used :
[tex]a=\frac{a_o}{2^n}[/tex]
where,
a = amount of reactant left after n-half lives = [tex]\frac{1}{8}a_o[/tex]
[tex]a_o[/tex] = Initial amount of the reactant
n = number of half lives
Putting values in above equation, we get:
[tex]\frac{1}{8}a_o=\frac{a_o}{2^n}[/tex]
[tex]2^n=8=2^3[/tex]
n = 3
Therefore, the number of half-lives it take will be, 3