(Venus, Mars) has evidence that water is or was once present.

Water is unique in that all three of its phases exist over a small range of pressures and temperatures, as shown in Figure 1.Figure 1  Phase diagram for waterIn the liquid phase, water dissolves and transports molecules, and aids in the biochemical reactions necessary to support life.  For this reason, scientists believe liquid-phase water is essential to the existence of extraterrestrial life.  Although it has been known for some time that water is present in both the gas and ice phases on Mars, the question remains as to whether there are regions where liquid-phase water can stably exist.  Estimates of Mars' surface temperature and pressure generated from satellite readings and global climate models, as well as observations made by Mars rovers, reveal that surface conditions on the planet can vary greatly.Table 1  Temperature and Pressure of Various Locations on MarsLocation/Mission Temperature PressureEstimated planetary average 218 K 6.00 mbViking I 256 K 7.11 mbPathfinder 260 K 6.60 mbSpirit 313 K 6.50 mbDespite the extremely low pressures and temperatures on Mars, satellite images have repeatedly found evidence of flowing liquid water in several regions during the late Martian summer season.  These regions, called recurring slope lineae (RSL), are hypothesized to be thermodynamically stable under certain Martian conditions due to the presence of dissolved salts.  A simple understanding of this hypothesis is afforded by Raoult's law, which states that the vapor pressure and freezing point of an ideal solution are lowered as the number of moles of dissolved solute increases.  Moreover, this effect also impacts the solution boiling point (the point at which the vapor pressure of the solution becomes equal to the ambient pressure).The briny-water hypothesis was confirmed in 2015 when spectral data from the Compact Reconnaissance Imaging Spectrometer onboard the Mars Reconnaissance Orbiter revealed the presence of hydrated perchlorates in the same regions and times that RSL were observed.  Studies are already underway to determine how common such briny water flows are and whether the conditions within them are suitable for microbial life. Question 6Which of the following affects the freezing point of an ideal solution?The strength of intermolecular forcesThe strength of intramolecular forcesThe melting point of the soluteA.I onlyB.II onlyC.I and III onlyD.II and III only

Is it likely that life ever existed on either Venus or Mars? Justify your answer in each case.

Select the best evidence to support the statement "Planets and moons are not the only places where one can find water in our solar system." There may be more than one correct choice.Ice is common in our solar system, from deposits at the poles of Mercury and the Moon to ice-covered moons and rings around distant Jupiter and Saturn. Scientists are studying ice on Earth and on other planets, in part because ice deposits could be a source of water for future explorers in the solar system.While the most common type of ice in our solar system is water ice, there are also many other types of ice. Mars' poles have abundant amounts of frozen carbon dioxide (also called dry ice), and comets have frozen ammonia and methane in addition to frozen water and other ices. Saturn's moon Titan is famous for its methane, which can exist not only as a liquid and gas at Titan's surface temperatures and pressures, but also as solid ice.

What is true of Mars?Group of answer choicesDefinite microfossils have been found.Its atmosphere is mostly water vapor.Iron oxide on the surface is responsible for its reddish color.A pool of water was discovered by the Mars Rover.Its magnetic field is stronger than Earth's

Water on Mars mostly exists in its solid state. Humans need liquid water to survive.Hypothesize how you would go about changing the state of water on Mars so humans can use it.