Consult to find (a) two metals less dense than water, (b) two metals more dense than mercury,(c) the densest known solid metallic element, and (d) the densest known solid nonmetallic element.

(a) lithium and potassium

(b) gold and osmium

(c) Osmium

(d) Iodine

Explanation:

(a) Metals generally have high density and high tensile strength. But the metals which have density even less than water are lithium and potassium.

The density of water = 1 g/cm³

Density of lithium = 0.53 g/cm³

Density of potassium = 0.59 g/cm³

(b) The two metals which are more denser than mercury are gold and osmium.

The density of mercury = 13.53 g/cm³

Density of gold = 19.3 g/cm³

Density of osmium = 22.59 g/cm³

(c) The value of density of osmium corresponds the maximum value of the density in the metals. Hence, osmium is the densest known solid metallic element.

(d) The value of density of iodine (4.94 g/cm³) corresponds the maximum value of the density in the non metals. Hence, iodine is the densest known solid non metallic element.

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.”

consider the reaction below.

 no rx

at 500 k, the reaction is at equilibrium with the following concentrations.

[pci5]= 0.0095 m

[pci3] = 0.020

[ci2] = 0.020 m

what is the equilibrium constant for the given reaction?

0.042

0.42

2.4

24