问题 选择题

向5 mL 18 mol/L的硫酸中加入足量铜片并加热使其充分反应,下列说法正确的是(  )

A.有0.09 mol的硫酸被还原

B.有0.045 mol的硫酸被还原

C.充分反应后体系无硫酸剩余

D.消耗的铜的质量一定小于2.88 g

答案

答案:D

浓硫酸与铜可发生氧化还原反应,而稀硫酸与铜不反应。浓硫酸与铜反应时,随着反应的进行,浓硫酸的浓度逐渐降低变成稀硫酸,因此实际参加反应的硫酸的量要比理论值小。根据题意可得n(H2SO4)=0.005 L×18 mol·L-1=0.09 mol,参加反应的硫酸n(H2SO4)<0.09 mol,被还原的硫酸小于0.045 mol,参加反应的铜的质量小于2.88 g。

单项选择题

As with any work of art, the merit of Chapman Kelley’s "Wildflower Works I" was in the eye of the beholder.

Kelley, who normally works with paint and canvas, considered the twin oval gardens planted in 1984 at Daley Bicentennial Park his most important piece.

The Chicago Park District considered it a patch of raggedy vegetation on public property that could be dug up and replanted at will like the flower boxes along Michigan Avenue. And that’s what happened in June 2004, when the district decided to create a more orderly vista for pedestrians crossing from Millennium Park via the new Frank Gehry footbridge.

If you’re looking for evidence that the rubes who run the Park District don’t know art when they see it, all you have to do is visit what’s left of Kelley’s masterpiece. The exuberant 1.5-acre tangle of leggy wildflowers is now confined to a tidy rectangle, restrained on all sides by a knee-high hedge and surrounded by a closely cropped lawn. White hydrangeas and pink shrub roses complete the look. We don’t know who’s responsible for the redesign, but we’ll bet the carpet in his home doesn’t go with the furniture.

Still, you’d think the Park District was within its rights to plow under the prairie. Wrong. Kelley just won at lawsuit in which he argued that the garden was public art and therefore protected by the federal Visual Artists Rights Act. Under that law, the district should have given him 90 days’notice that it intended to mess with his artwork instead of rushing headlong into the demolition, a la Meigs Field. That way Kelley could have mounted a legal challenge, or at least removed the plants.

Park District officials said they never considered the garden a work of art, even though it was installed by an established artist and not, say, Joe’s Sod and Landscaping. We can understand their confusion. Just recently, we figured out that the caged greenery directly south of Pritzker Pavilion is supposed to be an architectural statement and not a Christmas tree lot.

All that’s left is for the district to compensate Kelley for his loss. Whatever price the parties settle on, let’s hope the agreement also provides for the removal of the rest of "Wildflower Works I". If it wasn’t an eyesore before—and plenty of people thought it was—it sure is now.

The boldfaced word "rubes" in Paragraph 4 most likely means().

A. experts

B. laymen

C. fools

D. artists

单项选择题