(this question is from apex in course: physical science sem 2 which of the following are double-displacement reactions? check all that apply. a. hc2h3o2(aq) + nahco3(aq) → nac2h3o2(aq) + h2co3(aq) b. naoh(aq) + hci(aq) → naci(aq) + hoh(i) c. zn (s) + hci (aq) → znci2 (aq) + h2 (g) d. 2cu (s) + o2 (g) → 2cuo (s)

Check the correct box to describe the periodic trends in electronegativity. electronegativity across a period: decreases. increases. electronegativity down a group: decreases. increases.

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

8.98 dm3 of hydrogen gas is collected at 38.8 °c. find the volume the gas will occupy at -39.9 °c if the pressure remains constant.