Question:
Given below are two statements
Statement I: $\beta$-lactose anhydride is the common form of lactose crystals.
Statement II: $\alpha$-lactose monohydrate crystallises at a temperature above 95$^\circ$C from saturated solution of lactose.
In light of the above statements, choose the correct answer from the options given below:
Given below are two statements
Statement I: $\beta$-lactose anhydride is the common form of lactose crystals.
Statement II: $\alpha$-lactose monohydrate crystallises at a temperature above 95$^\circ$C from saturated solution of lactose.
In light of the above statements, choose the correct answer from the options given below:
Statement I: $\beta$-lactose anhydride is the common form of lactose crystals.
Statement II: $\alpha$-lactose monohydrate crystallises at a temperature above 95$^\circ$C from saturated solution of lactose.
In light of the above statements, choose the correct answer from the options given below:
Show Hint
Remember the lactose crystallization threshold:
- Below 95$^\circ$C $\rightarrow$ $\alpha$-lactose monohydrate (most common).
- Above 95$^\circ$C $\rightarrow$ $\beta$-lactose anhydride.
Updated On: Aug 5, 2026
- Both Statement I and Statement II are true
- Both Statement I and Statement II are false
- Statement I is true but Statement II is false
- Statement I is false but Statement II is true
Show Solution
Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept:
Lactose is a disaccharide that can exist in different crystalline and amorphous states.
The specific crystalline form that precipitates from a saturated aqueous solution depends on the temperature at which crystallization occurs.
Step 2: Detailed Explanation:
Let us evaluate both statements:
- Statement I: The most common, stable form of lactose crystals found in ordinary dairy products (such as milk powder, whey powder, and sweetened condensed milk) is $\alpha$-lactose monohydrate.
$\beta$-lactose anhydride is highly soluble and less common, typically obtained only under specific high-temperature conditions. Thus, Statement I is false.
- Statement II: The transition temperature for lactose crystallization in water is 95$^\circ$C.
When lactose is crystallized from a saturated solution at temperatures below 95$^\circ$C, the crystal form that precipitates is $\alpha$-lactose monohydrate.
If crystallization occurs at temperatures above 95$^\circ$C, the form that precipitates is $\beta$-lactose (specifically $\beta$-lactose anhydride).
Therefore, Statement II is false because $\alpha$-lactose monohydrate does not crystallize above 95$^\circ$C.
Consequently, both Statement I and Statement II are false.
Step 3: Final Answer
The correct option is (B).
Lactose is a disaccharide that can exist in different crystalline and amorphous states.
The specific crystalline form that precipitates from a saturated aqueous solution depends on the temperature at which crystallization occurs.
Step 2: Detailed Explanation:
Let us evaluate both statements:
- Statement I: The most common, stable form of lactose crystals found in ordinary dairy products (such as milk powder, whey powder, and sweetened condensed milk) is $\alpha$-lactose monohydrate.
$\beta$-lactose anhydride is highly soluble and less common, typically obtained only under specific high-temperature conditions. Thus, Statement I is false.
- Statement II: The transition temperature for lactose crystallization in water is 95$^\circ$C.
When lactose is crystallized from a saturated solution at temperatures below 95$^\circ$C, the crystal form that precipitates is $\alpha$-lactose monohydrate.
If crystallization occurs at temperatures above 95$^\circ$C, the form that precipitates is $\beta$-lactose (specifically $\beta$-lactose anhydride).
Therefore, Statement II is false because $\alpha$-lactose monohydrate does not crystallize above 95$^\circ$C.
Consequently, both Statement I and Statement II are false.
Step 3: Final Answer
The correct option is (B).
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