Please give answer to 83rd question with explanation

Please give answer to 83rd question with explanation 3 •their surface Of liquid e. Mhi*.' —ration is utilised daily lite in are roares tt Warming? "t are the factors •affecting Water evapora- house ton? water kept in earthern pots becomes much cooled. Very area. ligh i Wet hand on swinging feels cooling cimate change. Nature of substances ii. atmospheric tern. A sea , hittir€ prature reduced ircrease in tet i. Wind iv. Surface area (5) Due to me graph represent the change of state is Siseasemay happened to a molten substance at c. Avoeueexcesiveuseot cooling. Analysing the graph andan- • mer the following questions. hat is in- Temperature ±ated by 80 A part BC? hat is the 60 B tem- mature? What will 40 tie tem- perature 20 sub- sbnce after C • Redire the turmer S. cool day stel cooler than WOK*' plank. Since me srcifc than tat wyd. steel trom in cold to much cNier than 87. What is meant by u. Note Nat ot steam is util time df , 8 minutes? 0 M this graph indicates the so—en to to gas L No change in temperature. coed from B and completed at C. ii content" i.3(YC iii. 400C spread icy N.The part BC Wd countries salt is

Dear Student,
1. BC represents a change in phase of the substance.
We can say this because, during a phase change there is no rise in Temperature (As seen in the graph, the temperature remains constant at 60°C). All of the energy is used up in changing the substance from molten to solid state, hence no rise in Temperature during phase change. The substance in molten state solifies, therefore solidification takes place.
2. The lab temperature is 30°C. We can say this because there is no further change of state on decreasing the temperature. And, that the graph has been plotted only until point D.
3. The temperature of the substance after 6 mins is 40°C. If we extrapolate the graph upwards, we find that at 6 mins, the temperature is 40°C.
4. BC represents Solidification. As the substance is initially in the molten state(liquid state), during BC there is phase change( as represented by the constant temperature) and the substance has now changed to solid phase.

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