Two liquids $L_{1}$ and $L_{2}$ are at $20^{\circ}C$ and $40^{\circ}C$ respectively. When equal masses of them are mixed together the temperature of the mixture becomes $35^{\circ}C$. The ratio of specific heat capacities of $L_{1}$ and $L_{2}$ is:

By the principle of calorimetry, heat lost by the hotter liquid equals heat gained by the colder liquid, using the relation mass times specific heat times temperature change. Let the specific heats of L1 and L2 be S1 and S2; for equal masses m, the heat equation is m * S1 * (35 - 20) = m * S2 * (40 - 35). Simplifying this gives 15 * S1 = 5 * S2, which reduces to 3 * S1 = 1 * S2, making the ratio of their specific heat capacities S1 : S2 equal to 1 : 3.

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