30g Mg and 30g `O_(2)` are reacted and the residual mixture contains:

Options

A. 60g of MgO only
B. 40g of MgO and 20g of `O_(2)`
C. 45g of MgO and 15g of `O_(2)`
D. 50g of MgO and 10g of `O_(2)`

Answer

D

Explanation

`underset(2xx24g)underset(2"mol")(2Mg(s))+underset(1xx32g)underset(1"mol")(O_(2)(g)) to underset(2xx40g)underset(2"mol")(2MgO(g))`
`30"g Mg gives "((80)/(48)xx30)"` g MgO on complete reaction,
i.e. 30gMg=50g MgO
`30g O_(2)" gives "((80)/(48)xx30)"` MgO on complete reaction,
i.e.=30g `O_(2)-=75"g MgO"`
Mg is limiting reactant and MgO formed in the reaction will be 50g.
Unreacted amount of `O_(2)`=30-20=10g
Mixture contians 50g of MgO and 10g `O_(2)`.