Ques: Q: What molecule is made of two hydrogen atoms and one oxygen atom? Read this paragraph and choose the correct option from the provided answers: A molecule of water ( Figure below ) is made of three atoms bonded together. Two of these atoms are hydrogen and one atom is oxygen. The hydrogen ions have a positive electrical charge. The oxygen atom has a negative electrical charge. The hydrogen atoms are located on one side and the oxygen atom on the other. This means that the side with the hydrogen ions has a slightly positive charge. The other side, the side without the hydrogen ions, has a slightly negative charge. The water molecule is a polar molecule . Choices: - Oxygen - carbohydrate - lipids - water A:
Ans: water

Ques: Q: Boron only occurs naturally in compounds with what element? Read this paragraph and choose the correct option from the provided answers: Occurrence, Preparation, and Compounds of Boron and Silicon Boron constitutes less than 0.001% by weight of the earth's crust. In nature, it only occurs in compounds with oxygen. Boron is widely distributed in volcanic regions as boric acid, B(OH)3, and in dry lake regions, including the desert areas of California, as borates and salts of boron oxyacids, such as borax, Na2B4O710H2O. Elemental boron is chemically inert at room temperature, reacting with only fluorine and oxygen to form boron trifluoride, BF3, and boric oxide, B2O3, respectively. At higher temperatures, boron reacts with all nonmetals, except tellurium and the noble gases, and with nearly all metals; it oxidizes to B2O3 when heated with concentrated nitric or sulfuric acid. Boron does not react with nonoxidizing acids. Many boron compounds react readily with water to give boric acid, B(OH)3 (sometimes written as H3BO3). Reduction of boric oxide with magnesium powder forms boron (9598.5% pure) as a brown, amorphous powder: B 2 O 3(s) + 3Mg(s) 2B(s) + 3MgO(s) An amorphous substance is a material that appears to be a solid, but does not have a long-range order like a true solid. Treatment with hydrochloric acid removes the magnesium oxide. Further purification of the boron begins with conversion of the impure boron into boron trichloride. The next step is to heat a mixture of boron trichloride and hydrogen: 1500 C. Choices: - helium - nitrogen - carbon - oxygen A:
Ans: oxygen

Ques: Q: What are the two unique features of mollusks? Read this paragraph and choose the correct option from the provided answers: Two unique features of mollusks are the mantle and radula (see Figure above ). The mantle is a layer of tissue that lies between the shell and the body. It secretes calcium carbonate to form the shell. It forms a cavity, called the mantle cavity , between the mantle and the body. The mantle cavity pumps water for filter feeding. The radula is a feeding organ with teeth made of chitin. It is located in front of the mouth in the head region. Herbivorous mollusks use the radula to scrape food such as algae off rocks. Predatory mollusks use the radula to drill holes in the shells of their prey. Choices: - antennae and pseudopod - pseudopod and mantle - radula and antennae - mantle and radula A:
Ans: mantle and radula

Ques: Q: What is the rate at which energy is being transferred called? Read this paragraph and choose the correct option from the provided answers: Power is the rate at which energy is being transferred. Power tells you how many Joules per second of energy is being used to drive something. Thus power is simply the change in energy divided by the time. Since work is by definition the transfer of energy (in or out of a system), power is also equal to the work divided by the time. Efficiency tells you how efficient something is and gives a number between 0 and 1. If the efficiency is equal to 1, then the machine is perfectly efficient (that is all the power used to drive it goes to the out put of the machine with no energy losses). If the efficiency is zero, then all of the input power is lost in the machine and the machine can not output any energy. Choices: - electric - force - pressure - power A:
Ans:
power