The amount of heat energy needed to increase the temperature of a substance by [tex]\Delta T[/tex] is given by:
[tex]Q=m C_s \Delta T[/tex]
where m is the mass of the substance, Cs is its specific heat capacity and [tex]\Delta T[/tex] is the increase in temperature of the substance.
In this problem, we have a certain mass m of gold, with specific heat capacity [tex]C_s=0.126 J/g^{\circ}C[/tex], to which we add Q=2825 J of energy. Its temperature increases by [tex]\Delta T=60-25=35 ^{\circ}C[/tex]. Therefore, if we re-arrange the previous equation, we can find the mass of the block of gold:
[tex]m= \frac{Q}{C_s \Delta T} = \frac{2825J}{0.126\cdot 35}} =641 g[/tex]
So, the correct answer is B.
