The heat of combustion of carbon to `CO_(2)` is `-393.5` kJ/mol. The heat released upon formation of 35.2 g of `CO_(2)` from carbon and oxygen gas is

Options

A. `+315 kJ`
B. `- 31.5 kJ`
C. `-315 kJ`
D. `+31.5 kJ`

Answer

C

Explanation

`C+O_(2) rarr CO_(2) Delta H= -393.5kJ//mol`
`because` 44 gm of `CO_(2)` form by which heat released = `-393.5` kJ
`therefore` 1gm of `CO_(2)` form by which heat released `=- (393.5)/(44)`
`therefore` 35.2 gm (given) of `CO_(2)` form by which heat released
`= -(393.5)/(44) xx 35.2 = -315kJ`