`5g` of `KClO_(3)` gives `1.36 L` of oxygen at `STP`. The law of conservation of mass is valid within limits of ..........error.

Options

A. `+0.4%`
B. `-0.4%`
C. `+0.2%`
D. `-0.2%`

Answer

B

Explanation

`% "Error" = ("Error in mass")/("Total mass") xx 100%`
`KClO_(3) rarr KCl + O_(2)`
Sum total of mass of products `= Mass_(KCl) + Mass_(O_(2))`
`= (3.041g) + ((1.36)/(22.4) xx 32g)`
`(22.4 L O_(2)` at `STP` corresponds to 1 mol `O_(2) (i.e., 32g O_(2))`
`= (3.041g) + (1.94g)`
`= 4.98g`
Error in mass `= (5.00 - 4.98)g`
`= 0.02g`
`%` Error `= (0.02)/(5) xx 100% = 0.4%`