Can you ace this science quiz? Most Americans can't

Which of the earth's three layers is the hottest?

What does a light-year measure?

Who developed the polio vaccine?

A just-released survey from the Pew Research Center finds Americans' grasp of common science topics could be better.

More than 3,200 adults took the center's multiple-choice science quiz. Overall, they answered more questions correctly than incorrectly, but very few respondents -- only six percent -- got a perfect score on the 12-question test.

About a quarter of those surveyed answered eight or nine questions correctly, while another quarter answered 10 or 11 correctly. The median was eight correct answers out of the 12.

You can take the quiz on Pew's website -- and beware, spoilers ahead!

A large majority of people surveyed, 86 percent, knew the Earth's hottest layer (the core), and 78 percent correctly identified a photo and description of a comet, like the one pictured above.

About three-quarters knew the difference between astronomy and astrology,

But other science-related terms and concepts were tougher to understand. When asked to identify the effect of higher altitude on cooking time, just 34 percent knew that water boils at a lower temperature in Denver (a high-altitude setting) than it does in Los Angeles, near sea level.

And lots of people were stumped when asked to choose which property of a sound wave determines loudness (amplitude).

"As science issues become ever-more tied to policy questions, there are important insights that come from exploring how much Americans know about science," Cary Funk, the lead author and an associate director of research at Pew Research Center, said in a press release. "Science encompasses a vast array of fields and information. These data provide a fresh snapshot of what the public knows about some new and some older scientific developments -- a mixture of textbook principles covered in K-12 education and topics discussed in the news."

The survey found people with higher levels of education are more likely to know answers to questions about science. Those with a postgraduate degree got an average of 9.5 answers right, while people with a high school education or less got an average of 6.8 correct.

Gender and age were factors, too.

Men did better than women on many of the 12 questions, even when comparing men and women with similar levels of education. And younger adults, in general, had a slightly better overall grasp of science than seniors.

The researchers also found differences in science knowledge associated with race and ethnicity. Overall, whites were more likely than Hispanics or blacks to answer more of the questions correctly, though the pattern across these groups and the size of the differences varied, researchers noted.

The nationally representative survey of 3,278 randomly-selected adults was conducted Aug. 11-Sept. 3 2014.