Explanation:
(Ques- A) Why does the first method for determining volume work only for a regular-shaped object?
<u>(Ans- A)</u> <em>Because the method requires precise dimensions of objects for result, which is not possible for irregular shaped objects.</em>
(Ques - B) Will the second method for determining volume work for any object or just an odd-shaped one? Why?
<u>(Ans-B)</u> <em>It will work for both regular and irregular shaped objects since both displace equal volumes of water.</em>
(Ques - C) Is one method of measurement more accurate than the other? Why or why not?
<u>(Ans-C)</u> <em>Both are pretty accurate, with some experimental errors which may creep in accidentally. </em>
(Ques- D) Would the displacement method of measurement work for a cube of sugar? What about a cork? Why?
<u>(Ans - D)</u> <em>No, the method would not work because sugar being soluble, will dissolve in water. </em>
<em>No, the method would not work because sugar being soluble, will dissolve in water. Cork is less dense than water so floats on it, with only part of it submerged in water, resulting in displacement of less volume of water than actual volume of Cork.</em>
(Ques-E) What did you find out from this investigation? Be thoughtful in your answer.
<u>(Ans- E)</u> <em>I learnt about determining volume of different objects from this investigation. </em>(Sorry, I know its not a very thoughtful answer)
Answer:
Substances can change phase—often because of a temperature change. At low temperatures, most substances are solid; as the temperature increases, they become liquid; at higher temperatures still, they become gaseous.
The process of a solid becoming a liquid is called melting. (an older term that you may see sometimes is fusion). The opposite process, a liquid becoming a solid, is called solidification. For any pure substance, the temperature at which melting occurs—known as the melting point—is a characteristic of that substance. It requires energy for a solid to melt into a liquid. Every pure substance has a certain amount of energy it needs to change from a solid to a liquid. This amount is called the enthalpy of fusion (or heat of fusion) of the substance, represented as ΔHfus. Some ΔHfus values are listed in Table 10.2 “Enthalpies of Fusion for Various Substances”; it is assumed that these values are for the melting point of the substance. Note that the unit of ΔHfus is kilojoules per mole, so we need to know the quantity of material to know how much energy is involved. The ΔHfus is always tabulated as a positive number. However, it can be used for both the melting and the solidification processes as long as you keep in mind that melting is always endothermic (so ΔH will be positive), while solidification is always exothermic (so ΔH will be negative).
Table 10.2 Enthalpies of Fusion for Various Substances
Explanation:
It is more likely to be found as a COMPOUND, as it is more reactive, by the time we found them, they're already reacted with other elements or compounds to form new compounds.
Example is oxygen, it is very reactive, therefore we often found oxygen in water, which is H2O, in earth, instead of just pure oxygen.