Q73 (CAPF/2010) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Basic chemical principles Answer Verified

Statement I : Conversion of coal to diamond is a physical change. Statement I : Physical change does not change the composition of the material.

Both the statements are individually true and statement II is the correct explanation of statement I

Both the statements are individually true but statement II is not the correct explanation of statement I

Statement I is true but statement II is false

Statement I is false but statement II is true

Result

Your answer: — · Correct: D

Explanation

Statement I is false because the conversion of coal to diamond is a chemical change, not a physical one. While both are carbon-based, coal is an impure form of carbon containing elements like oxygen and hydrogen, whereas diamond is a pure crystalline allotrope [t6]. The transformation involves a fundamental change in chemical structure and bonding—from the amorphous, impure state of coal to the rigid, three-dimensional covalent network of diamond [c1, t4]. Statement II is true as a general definition: a physical change involves changes in physical properties (like state or shape) without altering the substance's chemical composition [c3, t1]. However, since the conversion of coal to diamond involves breaking and forming new chemical bonds and changing the purity/identity of the substance, it constitutes a chemical change [c4, t1]. Thus, Statement I is false and Statement II is true.

Sources

[1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Allotropes of carbon > p. 61
[2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > In a Nutshell > p. 68
[3] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > Activity 5.4: Let us experiment > p. 61

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Statement I : Conversion of coal to diamond is a physical change. Statement I : Physical change does not change the composition of the material.

Explanation

SIMILAR QUESTIONS

Statement I: Conversion of blue copper sulphate to black cupric oxide on heating is a physical change. Statement II : A change in which chemical composition does not change is called physical change.

Statement I: Diamond is very hard and has high melting point. Statement II : In diamond, each carbon is covalently bonded to four other carbon atoms to form a three-dimensional network.

Statement I : Diamond is very bright. Statement I : Diamond has very low refractive index.

Assertion (A) : A pure piece of diamond, on burning stronly, changes into CO2. Reason (R) : Diamond is made up of only carbon atoms.