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Chemistry · 2025 · 2 marks
CBSE 2025 · Region 1 · Set 1 · Q17
(A) Give reasons: (a) Cooking is faster in pressure cooker than in an open pan. (b) On mixing liquid X and liquid Y, volume of the resulting solution…
Give reasons :
(a)
Cooking is faster in pressure cooker than in an open pan.
(b)
On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution ? What change in temperature would you observe after mixing liquids X and Y ?
Define Azeotrope. What type of Azeotrope is formed by negative deviation from Raoult's law ? Give an example.
Marking-scheme solution
(A)(a)
Due to high pressure inside the pressure cooker, higher is the boiling point and
faster is the cooking.
(b)
Negative deviation
Temperature increases.
(B)
Same composition in liquid and in vapour phase and boil at a constant temperature.
Maximum Boiling Azeotrope
$\displaystyle 68$% HNO3 + $\displaystyle 32$% H2O (Percentage can be ignored)
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CBSE Class 12 Chemistry past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.