The molecular diagram of a substance is shown above. The first picture is the substance before it was heated. The second picture is the substance after it was heated. Which of the following state changes most likely occurred in the diagram above?

Assume you measured the mass of the cart to be (500 ± 1) g and the mass of the additional mass you put on the cart to be (500 ± 1) g as well. since the scale you are using in the lab cannot measure objects heavier than 600g you will have to sum up individual pieces and propagate the error. so what would be the mass and the standard error of the cart and the mass