The chemical reaction between `K_(2)C_(2)O_(4) and HgCl_(2)` is ,
`2HgCl_(2)+K_(2)C_(2)O_(4) rarr 2KCl +2CO_(2) +Hg_(2) Cl_(2)`
The weights of `Hg_(2)Cl_(2)` precipitated from different solutions in given time were taken and expressed as following :

Explanation

Let the rate law written as : `r=k[HgCl_(2)]^(x)[K_(2)C_(2)O_(4)]^(y)`
1. `(0.0032)/(60) =k [0.0418]^(x) [0.404]^(y)`
2. `(0.0068)/(65) =k [0.0836]^(x) [0.404]^(y)`
3. `(0.0031)/(120)=k[0.0836]^(x)[0.202]^(y)`
Solving the above equations, we get :
`x=1 and y=2`
order of reaction w.r.t.x =1 and y=2 and overall order is 3.