Question 16

which of these is an example of an amorphous solid?

diamonds

gold

sugar molecules

glass
3 points

question 17

which of these is true at equilibrium?

particles stop moving.

the number of particles in each phase increases.

the number of particles in each phase remains constant.

the number of particles in each phase decreases.
3 points

question 18

an increase in temperature will affect vapor pressure by:

decreasing the density of the gas molecules, making them lighter and easier to move around

increasing the average kinetic energy of the molecules, making them move faster and collide more

increasing the surface area of the gas molecules, thus increasing the number of collision points available

decreasing the rate of condensation
3 points

question 19

which of the following describes how vapor pressure and kinetic energy are related?

if kinetic energy of the particles is increased, vapor pressure will also increase.

if kinetic energy of the particles is increased, vapor pressure will decrease.

if kinetic energy of the particles is decreased, vapor pressure will increase.

kinetic energy and vapor pressure are not related.
3 points

question 20

at an elevation of 1200 feet (above sea level), it is easier to boil water because

the atmospheric pressure is higher at this elevation

the atmospheric pressure is lower at this elevation

the molecules of the water have less kinetic energy at this elevation

the water is warmer at this elevation
3 points

question 21

the process of deposition describes which of the following changes of state?

solid à liquid

gas à solid

liquid à gas

solid à gas
3 points

question 22

the process of evaporation describes which of the following changes of state?

solid à liquid

gas à solid

liquid à gas

solid à gas
3 points

question 23

what does the term normal in normal boiling point mean?

the pressure is at 100 degrees celsius.

the temperature is at 100 degrees celsius.

the pressure is at 1 atmosphere.

the temperature is at 1 atmosphere.
3 points

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.”