Describe how a physical property, such as mass or texture, can change without causing a change in the substance.

A substance is defined by its composition and structure (chemical bonds).

The composition is the ratio of the amount of each kind of atoms in the chemical formula, and the structue is how the atoms are bonded to each other.

Physical properties change when physical changes occurs: a deformation (change of form), a change of phase (e.g. melting or boiling), a separation (e.g. filtration or distilation) are changes of the appearance of the substance. But this kind of changes does not modifiy the composition and structure of the substance, so the substance remain being the same.

On the other hand, chemical properties are those that are observed when a substance ungergoes a chemical change (reaction). During the chemical reaation some chemical bonds will be broken and other will be formed, which will lead to one or more new different substances. Those different substances will have different structures and compositon than the original substance.

The reactant substances change and become the product substances, which, as said, have different composition (proportion of atoms).

pre-sliced bread is a relatively recent development in baking technology. previous to that, it was always sold in a bakery in daily-made contiguous loaves with no wrapping, and was moderately perishable, usually being used with a day or two (which is why every bakery had a discounted “day-old” bread table.) therefore, pre-sliced bread would grow stale quickly. the hard crust provided a protective layer, and once the exposed dry slice left from the previous cut was removed, the interior was still soft.

what keeps bread soft is the moisture retained in the crumb (the light spongy part that’s not crust). the reason the crust develops is the surface of the dough gets exposed to hot dry air during baking which browns the outer layer and seals it, preventing all the moisture from escaping the dough. longer exposure to air will also eventually cause your bread to lose flavor and become stale.

people were used to cutting slices as they needed them and storing bread in a specially-made wooden or metal breadbox or pail with a lid to preserve it longer, but the first automatically sliced commercial loaves were produced on july 6, 1928, in chillicothe, missouri, using a machine invented by otto rohwedder, an iowa-born, missouri-based jeweler.[1] pre-sliced bread would indeed dry out, were it not for another 20th century technology: the plastic bag. bread could now be pre-sliced, and if the enclosing bag remains sealed as much as possible, the bread will remain soft and fresh for longer than if sitting unwrapped on a shelf or enclosed in a bread box that is not air-tight. sealed packaging meant bread could also be sold on store shelves and eliminate frequent trips to a bakery.

sealing bread in a plastic bag had another effect: the moisture in the loaf will re-distribute into the crust and soften it, which is sometimes more pleasing in a sandwich - especially for children whose teeth might not yet be strong enough to tear through a hard crust. a homemade loaf of bread can be sealed in a bag overnight and the crust will become soft like store-bought sandwich bread.

these were novel changes in how bread was produced and sold, which led to the coining of the phrase “the greatest thing since sliced bread.”