Calculate the enthalpy change for the thermite reaction: 2al(s)+fe2o3(s)→2fe(s)+al2o3(s), δh∘rxn=−850 kj when 8.00 mol of al undergoes the reaction with a stoichiometrically equivalent amount of fe2o3. express your answer to three significant figures and include the appropriate units.

Enthalpy change for the balanced equation is -850kj
And from the balanced equation we come to know that for 2 moles of Al, the value is -850kj
for 1 mole of Al = -850/2 = -425 kj
We have to find the enthalpy change for 8 moles of Al = 8 x -425 = 3400kj
Thus, the enthalpy change for 8 mol of Al is -3400kj.

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic 

Only one reactant yields 2 or more products. meaning you will only have 1 product and it will break down into 2 or more products. eg. h2o -> h2 + o2