Question

How many grams of oxygen `(O_(2))` gas reacts completely with `1.0g` of calcium?
A. `0.6 g`
B. `1.6 g`
C. `4.0 g`
D. `0.4 g`

Answer 1

Correct Answer - D
`Ca + O_(2) rarr CaO`
According to formula,
Moles of `C` = Moles of `O`
`("Mass"_(Ca))/("Molar mass"_(Ca)) = ("Mass"_(O))/("Molar Mass"_(O))`
`(1g Ca)/(40g Ca) = (m_(O))/(16g O)`
`:. M_(O) = 0.4g`
We can use this approach because the enite `Ca` is changed into `CaO`.