30g of magnesium and 30g of oxygen are reacted and the residual mixture contains

Options

A. 45 g of magnesium oxide and 15g of oxygen
B. 50g of magnesium oxide and 10g of oxygen
C. 60g of magnesium oxide only
D. 40g of magnesium oxide and 20g of oxygen

Answer

B

Explanation

30 gram of Mg and 30 gram of `O_(2)` are reacted.
`2Mg+O_(2)=2MgO`
`2xx24` gram of magnesium combines with 32 gram of oxygen.
`therefore`30 gram of magnesium combines with
`(32xx30)/(2xx24)` gram of `O_(2)=20` gram of `O_(2)`.
Residual mixture contains (30-20) gram=10 gram
of `O_(2) and 50` gram of magnesium oxide.