I would like some help on this please.

I think it is the dark blue tile because if it is not soluble, or insoluble, then it will not dissolve and you will still see it floating around in the liquid or at the bottom of the container.

warm front forms when a moist, warm air mass slides up and over a cold air mass. as the warm air mass rises, it condenses into a broad area of clouds. a warm front brings gentle rain or light snow, followed by warmer, milder weather.

hope i !