Which statement best defines specific heat?
a. the amount of heat required to increase the temperature of 1 mol of a substance by 1 °c.
b. the amount of heat required to increase the temperature of 1 l of a substance by 1 °c.
c. the amount of heat required to increase the temperature of a specific object, such as a calorimeter, by 1 °c.
d. the amount of heat required to increase the temperature of 1 g of a substance by 1 °c.

D. The amount of heat required to increase the temperature of 1 g of a substance by 1 °C.

Explanation:

Specific heat is defined as the amount of heat needed to raise a unit of mass of a compound by one degree on the temperature scale.

The gram is constituted as a unit of mass, and the degree Celsius as a unit of temperature, therefore, the specific heat can be defined as the amount of heat required to increase the temperature of 1 g of a substance by 1 °C.

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

i believe the answer is three water molecules