Which of the following is true of folded mountains, fault-block mountains, and volcanic mountains? (2 points) form from the buildup of lava and ash form only at boundaries between two oceanic plates form only at boundaries between two continental plates form at both convergent and divergent plate boundaries

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

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