Answer the following question given this paragraph: All chemical changes involve a transfer of energy. When zinc reacts with hydrochloric acid, the test tube becomes very warm as energy is released during the reaction. Some other reactions absorb energy. While energy changes are a potential sign of a chemical reaction, care must be taken to ensure that a chemical reaction is indeed taking place. Physical changes also involve a transfer of energy. Melting of a solid absorbs energy, while the condensation of a gas releases energy. The only way to be certain that a chemical reaction has taken place is to test the composition of the substances after the change has taken place to see if they are different from the starting substances. Q: All chemical changes involve a transfer of what? Choices: - hydrogen - pressure - nitrogen - energy A:
energy
Answer the following question given this paragraph: Unit cells occur in many different varieties. As one example, the cubic crystal system is composed of three different types of unit cells: (1) simple cubic , (2) face-centered cubic , and (3) body-centered cubic . These are shown in three different ways in the Figure below . Q: The cubic crystal system is composed of how many different types of unit cells? Choices: - one - four - five - three A:
three
Q: Answer the following question given this paragraph: More than one force may act on an object at the same time. In fact, just about all objects on Earth have at least two forces acting on them at all times. One force is gravity, which pulls objects down toward the center of Earth. The other force is an upward force that may be provided by the ground or other surface. Q: How many forces do objects on earth have acting on them at all times? Choices: - ten - three - four - two A:
A: two
Question: Answer the following question given this paragraph: The kidneys filter all the blood in the body many times each day and produce a total of about 1.5 liters of urine . The kidneys control the amount of water, ions, and other substances in the blood by excreting more or less of them in urine. The kidneys also secrete hormones that help maintain homeostasis. Erythropoietin , for example, is a kidney hormone that stimulates bone marrow to produce red blood cells when more are needed. They also secrete renin, which regulates blood pressure, and calcitriol, the active form of vitamin D, which helps maintain calcium for bones. The kidneys themselves are also regulated by hormones. For example, antidiuretic hormone from the hypothalamus stimulates the kidneys to produce more concentrated urine when the body is low on water. Q: Which organ in the human body filters blood and excretes urine? Choices: - the liver - the bladder - the thyroid - the kidney A:
Answer: the kidney
*Question*
Answer the following question given this paragraph: Why does the pressure of a gas increase as it gets warmer? Particles of a gas are constantly moving and bumping into things. The force of the collisions is measured by pressure. Pressure is the amount of force exerted on a given area, such as pounds of force per square inch. When gas particles heat up and gain energy, they move faster. This causes more collisions and greater pressure. Therefore, heating particles of gas in a closed space causes the pressure of the gas to increase. Explore the behavior of gas particles at different temperatures at the following URL. Change the temperature of the gas and watch what happens to its particles. Q: If everything else stays the same in a system with a gas in it, and the gas gets warmer, what will happen to its pressure, generally? Choices: - it drops - it stays the same - it's eliminated - it increases A:
**Answer**
it increases
(Question)
Answer the following question given this paragraph: Fossils are the preserved remains or traces of organisms that lived long ago. They form mainly when minerals in water turn remains to stone. Fossils can be dated using methods such as carbon-14 dating or their positions in rock layers. Q: What term is defined as the preserved remains or traces of organisms that lived during earlier ages? Choices: - bones - waste - deposits - fossils A:
(Answer)
fossils