解：(1)Q吸=c奶m奶Δt奶=2.5×10^3J/(kg·℃)×250×10^-3kg×(40-10)℃=1.875×10^4J (2)m水=Q放/c水Δt水=Q吸/c水Δt水=1.875×10^4J/[4.2×10^3J/(kg·℃)×(60-40)℃]≈0.22kg
