Ques: Q: What holds ionic and covalent compounds together? Read this paragraph and choose the correct option from the provided answers: Ionic and covalent compounds are held together by electrostatic attractions between oppositely charged particles. Describe the differences in the nature of the attractions in ionic and covalent compounds. Which class of compounds contains pairs of electrons shared between bonded atoms?. Choices: - gravity - water - magnetic force - electrostatic attractions A:
Ans: electrostatic attractions

Ques: Q: The turbine of a windmill spins and creates what? Read this paragraph and choose the correct option from the provided answers: Wind power uses moving air as a source of energy. Some types of wind power have been around for a long time. People have used windmills to grind grain and pump water for hundreds of years. Sailing ships have depended on wind for millennia. Wind is now used to generate electricity. Moving air can make a turbine spin, just like moving water can. Moving air has kinetic energy. When wind hits the blades of the turbine, the kinetic energy makes the blades move. The turbine spins and creates electricity. Choices: - grains - pollution - lightning - electricity A:
Ans: electricity

Ques: Q: What is another name for a reasonable explanation for something that might be formed near the beginning of a scientific inquiry into a problem? Read this paragraph and choose the correct option from the provided answers: After doing the research, the farmer will try to answer the question. She might think, "If I don't plow my fields, I will lose less soil than if I do plow the fields. Plowing disrupts the soil and breaks up roots that help hold soil in place. " This answer to her question is a hypothesis . A hypothesis is a reasonable explanation. A hypothesis can be tested. It may be the right answer, it may be a wrong answer, but it must be testable. Once she has a hypothesis, the next step is to do experiments to test the hypothesis. A hypothesis can be proved or disproved by testing. If a hypothesis is repeatedly tested and shown to be true, then scientists call it a theory . Choices: - experiment - conclusion - theory - hypothesis A:
Ans: hypothesis

Ques: Q: Huge calderas form when the mountain above an empty chamber of what collapses? Read this paragraph and choose the correct option from the provided answers: During a massive eruption, all of the material may be ejected from a magma changer. Without support, the mountain above the empty chamber may collapse. This produces a huge caldera . Calderas are generally round, bowl-shaped formations ( Figure below ). Choices: - gas - mercury - coal - magma A:
Ans:
magma