Particulate Nature of Matter

After sugar dissolves in tea it can no longer be seen. Nandini says the sugar is gone. Maanav says it is still there and has only stopped being visible. If the glass were weighed before and after dissolving, what would happen?

A balloon full of air and an identical empty one — will they weigh the same? Ayesha says air has no weight, so yes. Tanvir says the filled balloon will weigh slightly more. Who is right?

Someone lights an incense stick in one corner. A few minutes later, in the closed room with the fan off, Anya smells it from the far side. Anya says someone must have carried it past her or a draught blew it over. Ravi says the smell spread there on its own. Who is right?

Half a glass of water left on a windowsill was empty after two days, though nobody drank it. Reshma says the water is finished. Jatin says the water is still in the room, just not visible. Who is right?

Rohit blocks the nozzle of a syringe. He can push the plunger of an air-filled one a long way in; the plunger of a water-filled one barely moves. Rohit says water is completely solid inside with no empty space, and air is just emptiness. Meena says both are made of particles and only the spacing differs. Who is right?

An ice cube was put on a steel plate and an identical one on a wooden board. The one on steel melted faster. Kamla says this is because steel is colder. Both had sat in the same room all night. Is her reason right?