A student records the conditions in a town at two different times. Time
Conditions
day bright and warm
night dark and cool
What causes the conditions experienced in the town at both times?
Day
Night
The Sun rotates away from the town
The Sun faces the town.
Day
Earth rotates the town
toward the Sun
Night
Earth rotates the town away from the
Sun
Day
Night
The Sun revolves to face away from
the town
The town faces the Sun
Day
Night
The Sun revolves to face the Earth revolves and the town faces away
town
from the Sun

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol