A `0.60 g` sample consisting of only `CaC_(2)O_(4)` and `MgC_(2)O_(4)` is heated at `500^(@)C`, converting the two salts into `CaCO_(3)" and "MgCO_(3)`. The sample then weighs `0.465 g`. If the sample had been heated to `900^(@)C`, where the products are CaO and MgO, what would the mixtures of oxides have weighed?

Options

A. `0.12 g`
B. `0.21 g`
C. `0.252 g`
D. `0.3 g `

Answer

C

Explanation

Let x g is wt. of `CaC_(2)O_(4)` and `(0.6-x) g` wt. of `MgC_(2)O_(4)`
`{:(CaC_(2)O_(4)overset(triangle)(to)CaCO_(3)+CO" "MgC_(2)O_(4) overset(triangle)(to)MgCO_(3)+CO),(128" "100" "112" "84):}`
Let .x. be the mass of `CaC_(2)O_(4)` and .y. be the mass of `MgC_(2)O_(4)` then `x+y=0.6`
`(x xx100)/(128)+(y xx84)/(112)=0.465`
On solving we get `x=0.48 g` and `y=0.12 g` wt. of CaO and MgO produced `=(0.48)/(128)xx56+(0.12)/(112)xx40 =0.252 g`.