1 g of an impure sample of magnesium carbonate (containing no thermally decomposable impurities) on complete thermal decomposition gave 0.44 g of carbon dioxide gas. The percentage of impurity in the sample is

Options

A. `0%`
B. `4.4%`
C. `16%`
D. `8.4%`

Answer

c

Explanation

`MgCO_(3) to MgO +CO_(2) uarr`
`MgCO_(3) : (1 xx 24 ) +(1 xx 12 ) + (3 xx 16) =84 g `
`CO_(2) : (1 xx 12 ) + (2 xx 16) = 44g`
100% pure 84 g `MgCO_(3)` on heating gives `44 g CO_(2)`
Given that 1 g of `MgCO_(3)` on heating gives `0.44 g CO_(2)`
Therefore, 84 g `MgCO_(3)` sample on heating gives 36.96 g `CO_(2)`
Percentage of purity of the sample `=(100%)/( 44 g CO_(2)) xx 36.96 g CO_(2)`
`=84%`
Percentage of impurity = 16 %