One molecule of dinitrogen tetroxide contains A two nitrogen atoms and two oxygen atoms.
.
B. four nitrogen atoms and two oxygen atoms.
Octwo nitrogen atoms and four oxygen atoms.
D. four nitrogen atoms and four oxygen atoms.

Cin carbonh in hydrogeno in oxygen

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other

Answermake them get very hot and over time wear them out;