PIMSO 2022 - Science - Grade 3 - National Round Question 9

Consider two completely identical containers, of the same, size, shape, volume and weight. One is filled with sugar the other is filled with salt. Both were completely filled up to the brim and closed. Then, their weights were measured and the one containing salt was found to be heavier.. Which of the following properties of the matter inside the two containers is NOT different between the two?

Editorial scope: choose the equality guaranteed by the stated measurements; color is not specified.