Gas hydrates are compact chemical structures made of natural gas and
a. halite.
b. water.
c. manganese.
d. petroleum.

                  Option-B (water) is the correct answer.

Explanation:

                 Gas hydrates are made up of Solid-Ice water and a natural gas like Methane gas trapped in the lattice of ice water. Gas hydrates are mainly found deep down in the sea where the atmospheric pressure is greater than 1 atm.

Generally Gas hydrates have two main applications. 

                             a) It stabilizes the sea floor other wise its melting will cause land sliding in sea floor. 

                             b) Secondly, it traps a green house gases like Methane, if released these gases could produce Climate changes.

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