SAT Reading and Writing · Topic 1.1
Central Ideas and Details Practice
Part of Information and Ideas.
Practice questions
76
Sample questions
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Sample 1difficulty 2/5
The northern lights — auroras — appear when charged particles from the Sun collide with gases in Earth's upper atmosphere. Different gases produce different colors: oxygen at high altitudes glows red, oxygen at lower altitudes glows green, and nitrogen contributes blues and purples. The displays vary with solar activity, becoming more intense and visible at lower latitudes during periods of strong solar storms.
Which choice best states the main idea of the text?
- A
Oxygen produces the brightest auroras.
- B
Solar storms are dangerous.
- Ccheck_circle
Auroras are caused by interactions between solar particles and atmospheric gases, with colors and intensity that depend on conditions.
- D
Auroras occur only at the poles.
Why
The passage describes the cause of auroras and the dependence of their appearance on conditions — A. B, C, and D are partial or unsupported.
- A
Sample 2difficulty 2/5
The speed of light in a vacuum, about 300,000 kilometers per second, is one of the few values in physics that appears the same to every observer regardless of motion. This counterintuitive fact, established by Einstein in his 1905 special theory of relativity, forces strange consequences: clocks run slower at high speeds, and lengths contract along the direction of motion.
Which choice best states the main idea of the text?
- A
Clocks are unreliable at high speeds.
- Bcheck_circle
The constancy of light's speed across observers is the foundation of special relativity's surprising consequences.
- C
Light travels at 300,000 kilometers per second.
- D
Einstein worked in 1905.
Why
The passage's central point is that the constancy underlies the strange consequences — A. B and C are facts; D misreads.
- A
Sample 3difficulty 2/5
Earthquakes occur when stress along a fault line exceeds the strength of the rocks holding it together, releasing built-up energy as seismic waves. Although small tremors can sometimes presage larger ones, scientists still cannot reliably predict when, where, or how strongly major earthquakes will strike. Building practices and preparedness, not prediction, remain the primary tools for limiting damage.
Which choice best states the main idea of the text?
- A
Most earthquakes are small.
- Bcheck_circle
Because earthquakes remain unpredictable, mitigation depends on building and preparedness, not prediction.
- C
Scientists can predict earthquakes accurately.
- D
Fault lines are the only source of seismic activity.
Why
The passage's central point is that limited predictability shifts the burden to mitigation — B. A contradicts; C and D are unsupported.
- A
Sample 4difficulty 2/5
The Rosetta Stone, discovered in 1799 by French soldiers in Egypt, bore the same decree in three scripts: hieroglyphic, demotic, and Greek. Because Greek was already understood, scholars could use the parallel texts to begin decoding hieroglyphics — a script that had been unreadable for over a thousand years. Jean-François Champollion's 1822 breakthrough opened the door to modern Egyptology.
Which choice best states the main idea of the text?
- Acheck_circle
The Rosetta Stone made it possible to decode hieroglyphics, transforming the study of ancient Egypt.
- B
Champollion was the founder of Egyptology.
- C
The Rosetta Stone was discovered by French soldiers.
- D
Hieroglyphics were difficult to read.
Why
The passage's main idea is the stone's role in enabling decipherment and modern Egyptology — C. A, B, and D are supporting details.
- A
Sample 5difficulty 2/5
The Sahara was not always a desert. Geological and archaeological evidence — fossil pollen, ancient lake beds, and rock art depicting crocodiles and giraffes — shows that as recently as 6,000 years ago, the region was a humid grassland. Shifts in Earth's orbital geometry gradually altered monsoon patterns, drying the landscape over millennia.
Which choice best states the main idea of the text?
- Acheck_circle
Multiple lines of evidence show the Sahara was once a humid grassland that dried over millennia.
- B
The Sahara has long been a desert.
- C
Rock art depicts crocodiles and giraffes.
- D
Earth's orbit changes constantly.
Why
The passage's main point is the Sahara's transformation, supported by varied evidence — C. A and D are details; B contradicts the text.
- A