Assertion (A) : A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter, the copper piece appears hotter than the glass piece. Reason (R) : The density of copper is more than that of glass.

Assertion is correct: when a copper piece and a glass piece are at the same temperature, the copper feels hotter because metals conduct heat much more rapidly, so they transfer thermal energy between skin and object faster than glass or other poor conductors [2]. The Reason statement — that copper’s higher density is responsible — is factually true (copper is denser than common glass) but it is not the causal explanation for the sensation. The perceived temperature on touch depends on heat-transfer properties (thermal conductivity and effusivity) and specific heat, not bulk density; hence R does not explain A [2].

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 4: The World of Metals and Non-metals > Activity 4.3: Let us investigate > p. 47
2. [2] https://van.physics.illinois.edu/ask/listing/44029