Explanation:
The law of conservation of matter states that the in chemical reaction the total mass on the left side of the equation should be equal to the total mass on the right side of the equation i.e. total mass on the both sides of the equation must be equal.
Option (1)
[tex]2Al+3O_2\rightarrow Al_2O_3[/tex]
Molar mass of reactant - [tex]2\times (26.98\ g/mol)+6\times (16\ g/mol)=149.96\ g/mol[/tex]
Molar mass of product - [tex]2\times (26.98\ g/mol)+3\times (16\ g/mol)=101.96\ g/mol[/tex]
LHS ≠ RHS
Law of conservation of matter not followed
Option (2)
[tex]4Al+O_2\rightarrow2Al_2O_3[/tex]
Molar mass of reactant - [tex]4\times (26.98\ g/mol)+2\times (16\ g/mol)=139.92\ g/mol[/tex]
Molar mass of product - [tex]4\times (26.98\ g/mol)+6\times (16\ g/mol)=203.92\ g/mol[/tex]
The law of conservation of matter is not followed.
Option (3)
[tex]2Al+O_2\rightarrow Al_2O_3[/tex]
Molar mass of reactant - [tex]2\times (26.98\ g/mol)+2\times (16\ g/mol)=85.96\ g/mol[/tex]
Molar mass of product - [tex]2\times (26.98\ g/mol)+3\times (16\ g/mol)=101.96\ g/mol[/tex]
The law of conservation of matter is not followed.
Option (4)
[tex]4Al+3O_2\rightarrow 2Al_2O_3[/tex]
Molar mass of reactant - [tex]4\times (26.98\ g/mol)+6\times (16\ g/mol)=203.92\ g/mol[/tex]
Molar mass of product - [tex]4\times (26.98\ g/mol)+6\times (16\ g/mol)=203.92\ g/mol[/tex]
LHS = RHS
The law of conservation of matter is followed. Hence, the correct option is (D).
