Answer the following question given this paragraph: All that changed when plants moved from water to land. This may have happened by 500 million years ago or even earlier. On land, everything was wide open. There were no other living things. Without plants, there was nothing for other organisms to eat. Land could not be colonized by other organisms until land plants became established. The earliest land plants may have resembled the modern liverworts in Figure below . Q: Land could not be colonized by other organisms until what became established? Choices: - gases - carbon dioxide - oxygen - plants A:
plants
(Question)
Answer the following question given this paragraph: Spiral galaxies have a rotating disk of stars and dust, a bulge in the middle, and several arms spiraling out from the center. The disk and arms contain many young, blue stars. Q: What type of galaxies have a rotating disk of stars and dust, a bulge in the middle, and several arms? Choices: - pinwheel galaxies - round galaxies - spherical galaxies - spiral galaxies A:
(Answer)
spiral galaxies
Ques: Answer the following question given this paragraph: Oxygen has the second highest electronegativity of any element; consequently, it prefers to share or accept electrons from other elements. Only with fluorine does oxygen form compounds in positive oxidation states. Q: Oxygen has the second highest electronegativity of any element; consequently, it prefers to share or accept electrons from other elements. only with fluorine does oxygen form compounds in this? Choices: - liquid oxidation states - chemical oxidation states - negative Oxidation States - positive oxidation states A:
Ans: positive oxidation states
(Q).
Answer the following question given this paragraph: The average particle energy needed to observe 19 GeV . (a) What unification of forces is estimated to be 10 is the rest mass in kilograms of a particle that has a rest mass 19 of 10 GeV/c 2 ? (b) How many times the mass of a hydrogen atom is this? 14. The peak intensity of the CMBR occurs at a wavelength of 1.1 mm. (a) What is the energy in eV of a 1.1-mm photon? (b) 9 There are approximately 10 photons for each massive 9 particle in deep space. Calculate the energy of 10 such photons. (c) If the average massive particle in space has a mass half that of a proton, what energy would be created by converting its mass to energy? (d) Does this imply that space is "matter dominated"? Explain briefly. (a) What Hubble constant corresponds to an approximate 10 age of the universe of 10 y? To get an approximate value, assume the expansion rate is constant and calculate the speed at which two galaxies must move apart to be separated by 1 Mly (present average galactic separation) in a time of 10 10 y. (b) Similarly, what Hubble constant corresponds to a 10 universe approximately 210 -y old? 16. Show that the velocity of a star orbiting its galaxy in a circular orbit is inversely proportional to the square root of its orbital radius, assuming the mass of the stars inside its orbit acts like a single mass at the center of the galaxy. You may use an equation from a previous chapter to support your conclusion, but you must justify its use and define all terms used. The core of a star collapses during a supernova, forming a neutron star. Angular momentum of the core is conserved, and so the neutron star spins rapidly. If the initial core radius 5 is 5.010 km and it collapses to 10.0 km, find the neutron star's angular velocity in revolutions per second, given the core's angular velocity was originally 1 revolution per 30.0 days. Using data from the previous problem, find the increase in rotational kinetic energy, given the core's mass is 1.3 times that of our Sun. Where does this increase in kinetic energy come from? 19.... Q: The core of a star collapses during what event, forming a neutron star? Choices: - spark - blast - gravitational - supernova A:
(A).
supernova
Ques:Answer the following question given this paragraph: Atoms have protons and neutrons in the center, making the nucleus, while the electrons orbit the nucleus. The modern atomic theory states that atoms of one element are the same, while atoms of different elements are different. What makes atoms of different elements different? The fundamental characteristic that all atoms of the same element share is the number of protons. All atoms of hydrogen have one and only one proton in the nucleus; all atoms of iron have 26 protons in the nucleus. This number of protons is so important to the identity of an atom that it is called the atomic number of the element. Thus, hydrogen has an atomic number of 1, while iron has an atomic number of 26. Each element has its own characteristic atomic number. Atoms of the same element can have different numbers of neutrons, however. Atoms of the same element (i. , atoms with the same number of protons) with different numbers of neutrons are called isotopes. Most naturally occurring elements exist as isotopes. For example, most hydrogen atoms have a single proton in their nucleus. However, a small number (about one in a million) of hydrogen atoms have a proton and a neutron in their nuclei. This particular isotope of hydrogen is called deuterium. A very rare form of hydrogen has one proton and two neutrons in the nucleus; this isotope of hydrogen is called tritium. The sum of the number of protons and neutrons in the nucleus is called the mass number of the isotope. Saylor URL: http://www. saylor. org/books. Q: All atoms of the same element share the same number of what type of particle? Choices: - quarks - neutrons - nucleus - protons A:

Ans:protons
Answer the following question given this paragraph: Fingernails and toenails consist of specialized epidermal cells that are filled with keratin. The keratin makes them tough and hard, which is important for the functions they serve. Fingernails prevent injury by forming protective plates over the ends of the fingers. They also enhance sensation by acting as a counterforce to the sensitive fingertips when objects are handled. Q: What makes toenails and fingernails hard? Choices: - guanine - cellulose - taurine - keratin A:
keratin