Answer the following question given this paragraph: The largest-mass stars become black holes . These extremely large stars end their life in the same way as a medium-mass star in that they become a supernova. After the outer layers are blown away in the supernova, however, the core of the star shrinks down in volume but still has a huge mass. The density of this object is extremely high, even denser than neutron stars. This dense object will have a gravitational force so large that not even light can escape from the body. (A companion topic to this occurs in The General Theory of Relativity where we see than extremely strong gravitational attraction can even attract light. ) These objects appear black because light cannot leave them, that is, they pull all light back to their surface. Black holes capture everything nearby due to their massive gravity and so they grow in size. Black holes are a common topic for science fiction but keep in mind, they are simply a very dense ball of matter with intense gravitational attraction. Q: Very large stars eventually become what extremely dense space regions, which are so dense that no light can escape from them? Choices: - worm holes - dark matter - moons - black holes A:
black holes
Answer the following question given this paragraph: Electroplating In a process called electroplating, a layer of a second metal is deposited on the metal electrode that acts as the cathode during electrolysis. Electroplating is used to enhance the appearance of metal objects and protect them from corrosion. Examples of electroplating include the chromium layer found on many bathroom fixtures or (in earlier days) on the bumpers and hubcaps of cars, as well as the thin layer of precious metal that coats silver-plated dinnerware or jewelry. In all cases, the basic concept is the same. A schematic view of an apparatus for electroplating silverware and a photograph of a commercial electroplating cell are shown in Figure 19.24 "Electroplating". Q: What is the process in which a layer of a second metal is deposited on the metal electrode that acts as the cathode during electrolysis? Choices: - casting - cold fusion - distillation - electroplating A:
electroplating
Q: Answer the following question given this paragraph: One way to keep iron from corroding is to keep it painted. The layer of paint prevents the water and oxygen necessary for rust formation from coming into contact with the iron. As long as the paint remains intact, the iron is protected from corrosion. Other strategies include alloying the iron with other metals. For example, stainless steel is mostly iron with a bit of chromium. The chromium tends to collect near the surface, where it forms an oxide layer that protects the iron. Zinc-plated or galvanized iron uses a different strategy. Zinc is more easily oxidized than iron because zinc has a lower reduction potential. Since zinc has a lower reduction potential, it is a more active metal. Thus, even if the zinc coating is scratched, the zinc will still oxidize before the iron. This suggests that this approach should work with other active metals. Another important way to protect metal is to make it the cathode in a galvanic cell. This is cathodic protection and can be used for metals other than just iron. For example, the rusting of underground iron storage tanks and pipes can be prevented or greatly reduced by connecting them to a more active metal such as zinc or magnesium (Figure 17.18). This is also used to protect the metal parts in water heaters. The more active metals (lower reduction potential) are called sacrificial anodes because as they get used up as they corrode (oxidize) at the anode. The metal being protected serves as the cathode, and so does not oxidize (corrode). When the anodes are properly monitored and periodically replaced, the useful lifetime of the iron storage tank can be greatly extended. Q: Zinc is more easily oxidized than iron because zinc has a lower reduction potential. since zinc has a lower reduction potential, it is a more what? Choices: - much metal - Trap metal - usually metal - active metal A:
A: active metal
Question: Answer the following question given this paragraph: By giving birth to tiny embryos, marsupial mothers are at less risk. However, the tiny newborn marsupial may be less likely to survive than a newborn placental mammal. The marsupial embryo completes its growth and development outside the mother's body in a pouch. It gets milk by sucking on a nipple in the pouch. There are very few living species of marsupials. They include kangaroos, koalas, and opossums. You can see a baby koala peeking out of its mother's pouch in Figure below . Q: Kangaroos, koalas, and opossums are examples of what type of mammals? Choices: - carnivorous - cephalopods - monotremes - marsupials A:
Answer: marsupials
*Question*
Answer the following question given this paragraph: Veins are made primarily of xylem and phloem. They transport water and minerals to the cells of leaves and carry away dissolved sugar. Q: What are xylem and phloem responsible for transporting to the cells of leaves? Choices: - air and dirt - water and blood - light and gas - water and minerals A:
**Answer**
water and minerals
Answer the following question given this paragraph: Mistakes may occur during meiosis that result in nondisjunction . This is the failure of replicated chromosomes to separate during meiosis (the animation at the link below shows how this happens). Some of the resulting gametes will be missing a chromosome, while others will have an extra copy of the chromosome. If such gametes are fertilized and form zygotes, they usually do not survive. If they do survive, the individuals are likely to have serious genetic disorders. Table below lists several genetic disorders that are caused by abnormal numbers of chromosomes. Most chromosomal disorders involve the X chromosome. Look back at the X and Y chromosomes and you will see why. The X and Y chromosomes are very different in size, so nondisjunction of the sex chromosomes occurs relatively often. http://learn. genetics. utah. edu/content/begin/traits/predictdisorder/index. html. Q: What is the failure of replicated chromosomes during meiosis to separate known as? Choices: - pollenation - regression - separation - nondisjunction A:
nondisjunction