AccelePrep for the ACT Test 2nd Edition Student Text

232 • S URGE TO S UCCESS ! S CIENCE T EST P REP

24. Which of the following single changes to š’‡”‹‡– ʹ ™‘—Ž† ’”‘†—…‡ ƒ…—””‡– ‘ˆ ͲǤͲͲͶ ƒ’‡”‡•ǫ F. Decrease the voltage to 4 volts. G. Decrease the voltage to 8 volts. H. Increase the resistance to 4,000 ohms. J. Increase the resistance to 2,000 ohms. PASSAGE V Phase diagrams illustrate the relationship between temperature, pressure, and the phases of matter. Each of the three phases—solid, liquid, and gas—is represented by a section of the phase diagram. The curves represent states of equilibrium between two phases—the substance is present in two phases at once as it passes from one phase to –Š‡ ‡š–Ǥ ŽŽ –Š”‡‡ ’Šƒ•‡• ƒ”‡ ’”‡•‡– ƒ– –Š‡ –”‹’Ž‡ point. For temperatures and pressures both below the triple point, matter passes directly between the solid and gas phases without passing through the liquid phase. For pressures and temperatures beyond the critical point, the liquid and gas phases converge and become indistinguishable in what is known as a •—’‡”…”‹–‹…ƒŽ ϐŽ—‹†Ǥ —’‡”…”‹–‹…ƒŽ ϐŽ—‹†•…ƒ †‹••‘Ž˜‡ materials like a liquid and effuse through solids like a gas. Beyond the critical point, no amount of ’”‡••—”‡ ™‹ŽŽ ”‡•–‘”‡ ƒ •—’‡”…”‹–‹…ƒŽ ϐŽ—‹† –‘ ‹–• Ž‹“—‹† or solid phase without decreasing the temperature. Figure 1 shows the phase diagram for water, a liquid at room temperature (21 q C) and atmospheric pressure (1 atm). Figure 2 shows the phase diagram ˆ‘”…ƒ”„‘ †‹‘š‹†‡ǡ ƒ ‰ƒ• ƒ– ”‘‘ –‡’‡”ƒ–—”‡ ƒ† atmospheric pressure.

Figure 1

Figure 2