The constant used for the absorption of heat by the sample in melting is [tex]+\Delta H_{fus}[/tex]. Thus, option A is correct.
The chemical reaction has been defined as the energy in which the energy has been released or absorbed for the breaking of bonds in the reactants and the formation of product.
The energy has been absorbed in the melting of the copper sample. Thus, the sample has been converted from the solid to the liquid state.
The change in energy with the conversion in solid and liquid state has been termed as heat of fusion.
The energy has been absorbed by the system, thus it has been marked with the positive sign.
Therefore, [tex]+\Delta H_{fus}[/tex] has been the constant used for the absorption of heat by the sample in melting. Thus, option A is correct.
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