From vibrant yellow to dull brown, Vincent would not be happy. Vincent Van Gogh painted some of the most vividly colored paintings in the Impressionist era. For several years, however, art conservationists have been noticing a problem. Some of the brilliant yellow sunflowers have been turning a muddy brown. This is due to a chemical reaction in the paint. They need to find a way to stop it. The first step is to understand the reason for this chemical reaction. Van Gogh's use of bold, bright colors, especially yellow, was new tothe art world of the late 1800s. There was a new type of pigmentcalled “chrome yellow.” Van Gogh realized that it could
create vivid, lively colors and used it often in his paintings. However,
the bright yellow pigment tends to turn brown after years of exposure to ultraviolet rays, including sunlight. This is due to a chemical reaction in the outer layers of paint.
To learn why this was happening, researchers used x-rays to analyze the exact chemical composition of the paint as it browned. Different artists mixed the pigment with different chemicals to produce paint. The researchers started with three different historically accurate chrome yellow mixtures. Then they artificially “aged” the pigments by exposing them to UV radiation until one of them turned a rich brown. They then identified the changes in that paint's chromium compounds. Next, they had to determine if the chemical changes in the sample were the same as in the brown from Van Gogh’s paintings. They compared the results of the artificial aging with a very small sample of one of Van Gogh's paintings. Their suspicions were confirmed. The two paints behaved similarly in their chemical reactions.
The scientists had shown that the paint pigments Van Gogh used were chemically similar to the ones that had been artificially aged. Barium and sulfur were in the white paint that Van Gogh used to mix with the chrome yellow pigment. Scientists suspect that either barium or sulfur is the reactant in the chemical reaction with the yellow chromium. One of the products is a new chromium compound with different properties and a brown color.
Scientists and art conservationists all agree that Van Gogh's paintings must be protected from UV radiation, particularly sunlight, to prevent them from turning brown. They are still trying to find a chemical antidote. They must identify a process to prevent the chemical reaction. Until then, Van Gogh's flowers shouldn’t be exposed to sunlight.

Question 1
Based on this passage, which of these is the most accurate description of the job of an art conservationist?

A. Mix different types of paint samples

B. Preserve paintings and other works of art

C. Buy and sell paintings

D. Operate x-ray machines

Question 2

What would be the most likely explanation if none of the tested paint samples had turned brown?

A. The reaction was not actually caused by UV light.

B. The reaction only happens in real sunlight, not artificial light.

C. The paint behaves differently on a canvas than it does in a laboratory.

D. None of the tested mixtures matched the chemical composition of Van Gogh's paint.

Question 3

How did modern scientists experiment with Van Gogh's paints to determine their chemical reactions?

A. They used x-ray analysis.

B. They used litmus testing.

C. They burned the paint to examine what elements were left after the chromium was burned off.

D. They compared the density of modern yellow paint to that of 100-year-old paint.

Question 4

Which words help the reader determine the meaning of the word vividly in the first paragraph?

A. Art conservationists

B. Impressionist era

C. Brilliant yellow

D. Muddy brown

Question 5

What is the main point of the passage?

A. Ultraviolet rays can cause chemical reactions.

B. Van Gogh was the most famous painter of the Impressionist era.

C. Art conservationists can always restore art.

D. Artists' paints can eventually damage the canvasses.