Answer:
The dihedral angle between the X substituents for the anti conformation is 180°
Step-by-step explanation:
Note: I think this question is not complete. Still, it can be answered. But for your concept and understanding, I am completing this question and then I will try to solve this question for you.
Other part of this question is about Gauche conformations and angle between the x substituents.
So, I will be drawing and answering both.
Answer to the original question: 180°
So, the dihedral angle between the X substituents for the anti conformation is 180°
Answer to the Gauche Conformation: 60°
Here, in this question we are discussing about the possible different staggered conformations of CH2XCH2X
You can see the angles between the X substitutes in anti conformations and Gauche Conformations for yourself in the attachment below.
Furthermore, this CH2XCH2X has 3 possible different staggered conformations. Out of which, one is anti conformation and other two are Gauche conformations.
Please refer to the attachment to see the conformations. Check the angles between X-X. In anti conformation, angle between X-X is 180° and energy is lower, because of the less interaction between H and X. However, in Gauche conformation, angle between X-X is 60° and energy is higher, because of the more interactions between H and X than anti conformation.