Why should we learn reaction types in pairs?

Fill in the coefficients that will balance the following reaction: a0cr2(so4)3 + a1agno3 -> a2cr(no3)3 + a3ag2so4

Compare and contrast the bohr model and the electron cloud models of the atom.

Rocks, as they are compressed, begin forming mountains above the earth's surface when two continental plates converge. the continental crust increases in depth as the mountains grow above. the himalayan mountains formed at a convergent plate boundary in this manner. the rocks are smashed together causing them to due to the intense heat and pressure from the colliding plates and eventually forming rock. a) melt; igneous b) layer; sedimentary c) recrystallize; metamorphic d) melt into the earth's interior; metamorphic