Part I — Questions 1–25

1. The Sun is classified as a:
   A. Planet
   B. Star
   C. Satellite
   D. Comet
   Correct Answer: B — Star
   Explanations:
   A: Incorrect — planets orbit stars; the Sun is not a planet.
   B: Correct — the Sun produces its own light and heat, characteristic of a star.
   C: Incorrect — a satellite orbits a planet; the Sun is central, not orbiting a planet.
   D: Incorrect — comets are icy bodies with tails, not self-luminous like the Sun.

2. Which object orbits the Earth?
   A. Sun
   B. Mars
   C. Moon
   D. Jupiter
   Correct Answer: C — Moon
   Explanations:
   A: Incorrect — the Sun does not orbit Earth; Earth orbits the Sun.
   B: Incorrect — Mars orbits the Sun, not Earth.
   C: Correct — the Moon is Earth’s natural satellite and orbits Earth.
   D: Incorrect — Jupiter orbits the Sun.

3. One complete rotation of Earth on its axis gives us:
   A. One year
   B. One day (day and night)
   C. A season
   D. A lunar month
   Correct Answer: B — One day (day and night)
   Explanations:
   A: Incorrect — one year is Earth’s revolution around the Sun.
   B: Correct — Earth’s rotation (~24 hours) causes day and night.
   C: Incorrect — seasons result from Earth’s revolution combined with axial tilt.
   D: Incorrect — a lunar month relates to the Moon’s phases, not Earth’s rotation.

4. The time Earth takes to complete one revolution around the Sun is about:
   A. 24 hours
   B. 365 days (1 year)
   C. 7 days
   D. 30 days
   Correct Answer: B — 365 days (1 year)
   Explanations:
   A: Incorrect — 24 hours is one rotation, not revolution.
   B: Correct — Earth takes ~365 days to orbit the Sun.
   C: Incorrect — 7 days is a week, unrelated to orbit time.
   D: Incorrect — 30 days approximates a month, not a year.

5. The shape of the path followed by Earth around the Sun is called:
   A. Straight line
   B. Circle
   C. Ellipse (nearly circular)
   D. Triangle
   Correct Answer: C — Ellipse (nearly circular)
   Explanations:
   A: Incorrect — Earth’s path is curved, not straight.
   B: Incorrect — it’s not a perfect circle; it’s slightly elliptical.
   C: Correct — planetary orbits are ellipses (Kepler’s first law); Earth’s is nearly circular.
   D: Incorrect — orbits are not triangular.

6. Which planet is known as the Red Planet?
   A. Venus
   B. Mars
   C. Mercury
   D. Saturn
   Correct Answer: B — Mars
   Explanations:
   A: Incorrect — Venus is bright and yellowish-white in appearance.
   B: Correct — Mars appears reddish due to iron-oxide (rust) on its surface.
   C: Incorrect — Mercury is grey and cratered.
   D: Incorrect — Saturn is pale yellow and has rings.

7. Which one of the following has rings around it?
   A. Earth
   B. Neptune
   C. Saturn
   D. Mercury
   Correct Answer: C — Saturn
   Explanations:
   A: Incorrect — Earth has no prominent ring system.
   B: Incorrect — Neptune has faint rings but they are not as prominent as Saturn’s.
   C: Correct — Saturn is famous for its distinct and extensive ring system.
   D: Incorrect — Mercury has no rings.

8. A natural satellite is:
   A. A man-made object orbiting Earth
   B. An object made by nature that orbits a planet
   C. A planet that orbits the Sun
   D. A star
   Correct Answer: B — An object made by nature that orbits a planet
   Explanations:
   A: Incorrect — man-made objects are artificial satellites.
   B: Correct — natural satellites (e.g., the Moon) are natural bodies orbiting planets.
   C: Incorrect — planets orbit the Sun (or stars), not classified as satellites of planets (except moons).
   D: Incorrect — stars are luminous bodies, not satellites of planets.

9. The Moon reflects light because:
   A. It produces its own light
   B. It is a star
   C. Sunlight falls on it and reflects back
   D. It glows by itself
   Correct Answer: C — Sunlight falls on it and reflects back
   Explanations:
   A: Incorrect — the Moon does not generate light.
   B: Incorrect — the Moon is not a star.
   C: Correct — we see the Moon because it reflects sunlight.
   D: Incorrect — the Moon does not glow by its own energy.

10. During a lunar eclipse:
    A. Earth comes between Sun and Moon, casting a shadow on the Moon
    B. Moon comes between Sun and Earth
    C. Sun is hidden by the Moon for Earth
    D. Moon shines brighter than usual
    Correct Answer: A — Earth comes between Sun and Moon, casting a shadow on the Moon
    Explanations:
    A: Correct — lunar eclipse occurs when Earth’s shadow falls on the Moon.
    B: Incorrect — that describes a solar eclipse.
    C: Incorrect — a solar eclipse is Sun being hidden from part of Earth by the Moon.
    D: Incorrect — lunar eclipse makes the Moon darker (often reddish), not brighter.

11. A solar eclipse happens when:
    A. Moon moves into Earth’s shadow
    B. Earth moves into Sun’s shadow
    C. Moon comes between Sun and Earth and blocks Sun’s light
    D. Sun goes behind Jupiter
    Correct Answer: C — Moon comes between Sun and Earth and blocks Sun’s light
    Explanations:
    A: Incorrect — that is lunar eclipse.
    B: Incorrect — Earth does not move into the Sun’s shadow; Earth’s shadow falls on the Moon during lunar eclipse.
    C: Correct — in a solar eclipse the Moon blocks sunlight from reaching parts of Earth.
    D: Incorrect — Sun does not go behind Jupiter from our viewpoint for eclipses.

12. Phases of the Moon are caused by:
    A. Earth’s shadow only
    B. The Moon’s atmosphere
    C. Changing positions of the Moon relative to Earth and Sun
    D. Clouds covering the Moon
    Correct Answer: C — Changing positions of the Moon relative to Earth and Sun
    Explanations:
    A: Incorrect — Earth’s shadow causes lunar eclipse, not the regular phases.
    B: Incorrect — the Moon has a negligible atmosphere; phases aren’t due to atmosphere.
    C: Correct — phases result from which part of the Moon is lit by the Sun as it orbits Earth.
    D: Incorrect — clouds may hide the Moon but don’t create phases.

13. When the Moon is between the Earth and Sun, the Moon’s phase is:
    A. Full Moon
    B. New Moon
    C. First quarter
    D. Last quarter
    Correct Answer: B — New Moon
    Explanations:
    A: Incorrect — full Moon is opposite: Earth between Sun and Moon.
    B: Correct — New Moon occurs when the Moon is roughly between Sun and Earth, its near side is dark.
    C: Incorrect — first quarter occurs when half the Moon is visible after new Moon.
    D: Incorrect — last quarter (third quarter) is half visible before new Moon.

14. The brightest object in the night sky (after Moon) seen from Earth is usually:
    A. Mars
    B. Venus
    C. Polaris
    D. Jupiter
    Correct Answer: B — Venus
    Explanations:
    A: Mars is bright at times but usually not as bright as Venus.
    B: Correct — Venus is very bright because of reflective clouds and closeness to Earth.
    C: Incorrect — Polaris (North Star) is not the brightest.
    D: Incorrect — Jupiter can be bright but usually less than Venus.

15. Artificial satellites are launched for all except:
    A. Weather forecasting
    B. TV broadcasting
    C. Producing sunlight
    D. Communication and navigation
    Correct Answer: C — Producing sunlight
    Explanations:
    A: Incorrect — many satellites monitor weather; this is a real use.
    B: Incorrect — TV signals are relayed via satellites.
    C: Correct — satellites do not produce sunlight.
    D: Incorrect — satellites support communication and navigation (e.g., GPS).

16. Which of these is a natural satellite of Earth?
    A. Sputnik (man-made)
    B. Moon
    C. Hubble Space Telescope
    D. ISS (International Space Station)
    Correct Answer: B — Moon
    Explanations:
    A: Incorrect — Sputnik was a man-made satellite.
    B: Correct — the Moon is Earth’s only natural satellite.
    C: Incorrect — Hubble is an artificial satellite (space telescope).
    D: Incorrect — ISS is a human-made space station.

17. Which star appears fixed in the sky and helps in navigation?
    A. Sun
    B. Venus
    C. Polaris (North Star)
    D. Betelgeuse
    Correct Answer: C — Polaris (North Star)
    Explanations:
    A: Incorrect — the Sun moves across our sky daily (apparent motion); Polaris appears nearly fixed.
    B: Incorrect — Venus moves in the sky relative to stars.
    C: Correct — Polaris is close to the North Celestial Pole and appears fixed for northern observers.
    D: Incorrect — Betelgeuse is a bright star but not fixed for navigation like Polaris.

18. A comet is best described as:
    A. A burning piece of rock like the Sun
    B. A small icy body that develops a glowing head and tail near the Sun
    C. An artificial satellite
    D. A type of planet
    Correct Answer: B — A small icy body that develops a glowing head and tail near the Sun
    Explanations:
    A: Incorrect — comets are not self-luminous like the Sun.
    B: Correct — when comets approach the Sun, ice vaporizes creating coma and tail.
    C: Incorrect — comets are natural astronomical bodies, not man-made.
    D: Incorrect — comets are distinct from planets.

19. Which of the following is NOT a planet of our solar system?
    A. Mercury
    B. Pluto (dwarf planet)
    C. Earth
    D. Neptune
    Correct Answer: B — Pluto (dwarf planet)
    Explanations:
    A: Incorrect — Mercury is a planet.
    B: Correct — Pluto is classified as a dwarf planet, not one of the eight major planets.
    C: Incorrect — Earth is a planet.
    D: Incorrect — Neptune is a planet.

20. Which phenomenon explains why astronauts float inside an orbiting spacecraft?
    A. No gravity in space at all
    B. Spaceship engines make them float
    C. Free-fall (microgravity) — both spacecraft and astronauts fall around Earth together
    D. Moon’s pull only
    Correct Answer: C — Free-fall (microgravity) — both spacecraft and astronauts fall around Earth together
    Explanations:
    A: Incorrect — gravity acts in low Earth orbit but objects are in continuous free-fall.
    B: Incorrect — engines don’t make them float; orbiting causes weightlessness.
    C: Correct — orbiting is a state of continuous free-fall producing microgravity and apparent weightlessness.
    D: Incorrect — Moon’s pull is negligible for astronauts in LEO; primary is Earth’s gravity.

21. Which of these planets is closest to the Sun?
    A. Earth
    B. Mercury
    C. Mars
    D. Venus
    Correct Answer: B — Mercury
    Explanations:
    A: Incorrect — Earth is third from the Sun.
    B: Correct — Mercury is the innermost planet.
    C: Incorrect — Mars is fourth from the Sun.
    D: Incorrect — Venus is second from the Sun.

22. Stars appear to twinkle because of:
    A. Stars turning on and off
    B. Movement of the stars themselves rapidly
    C. Atmospheric disturbances in Earth’s atmosphere
    D. The Sun’s light interfering with stars
    Correct Answer: C — Atmospheric disturbances in Earth’s atmosphere
    Explanations:
    A: Incorrect — stars do not turn on/off in short timescales.
    B: Incorrect — stars are far away and their motion is not perceptible as twinkling.
    C: Correct — Earth’s atmosphere refracts starlight causing twinkling.
    D: Incorrect — the Sun does not cause twinkling of night stars.

23. Which of the following instruments helps to view distant stars and planets?
    A. Microscope
    B. Thermometer
    C. Telescope
    D. Barometer
    Correct Answer: C — Telescope
    Explanations:
    A: Incorrect — microscope is for tiny, close objects.
    B: Incorrect — thermometer measures temperature.
    C: Correct — telescopes collect light from distant celestial objects for observation.
    D: Incorrect — barometer measures atmospheric pressure.

24. Which of the following is essential for life on Earth and comes from the Sun?
    A. Gravity only
    B. Light and heat
    C. Artificial satellites
    D. Moonlight only
    Correct Answer: B — Light and heat
    Explanations:
    A: Incorrect — gravity is essential but not produced by the Sun for Earth’s existence.
    B: Correct — Sun provides energy in the form of light and heat for life processes (photosynthesis, climate).
    C: Incorrect — satellites are human-made, not essential for life.
    D: Incorrect — moonlight is reflected sunlight and much weaker than direct sunlight.

25. The group of stars that forms a pattern in the sky is called a:
    A. Galaxy
    B. Planetary system
    C. Constellation
    D. Nebula
    Correct Answer: C — Constellation
    Explanations:
    A: Incorrect — galaxy is a vast collection of stars (e.g., Milky Way), not just a pattern.
    B: Incorrect — planetary systems include a star and its planets.
    C: Correct — constellations are recognizable star patterns named historically (e.g., Orion).
    D: Incorrect — a nebula is a cloud of gas and dust in space.

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