Class 10th Science Chapter 1: Our Universe Quiz

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12 Questions

What is the universe?

An unimaginably vast expanse with stars and galaxies

According to the Big Bang Theory, how did the universe begin?

As an incredibly hot and dense singularity around 13.8 billion years ago

Which celestial body lies at the center of our solar system?

The Sun

How many planets are there in our solar system?


What is the Milky Way?

A collection of billions of stars, gas, and dust

What is the name of our galaxy?

Milky Way Galaxy

What percentage of the universe is composed of dark energy?


How does the diameter of an atom compare to the diameter of a red blood cell?

A red blood cell is bigger

What is the approximate diameter of the Milky Way galaxy?

100,000 light years

Which component of the universe is inferred based on gravitational effects, but is difficult to detect?

Dark matter

What is the most convincing evidence supporting the Big Bang Theory?

The faint glow that fills the universe

In terms of size, how does the Earth compare to Jupiter?

Earth is bigger

Study Notes

Class 10th Science Chapter 1: Our Universe

Welcome to the very first chapter of your Class 10 Science journey! In this chapter, we'll embark on an exploration of the universe, the grand stage on which the story of life unfolds. Let's dive right in and discover the fascinating secrets of our cosmos.

What is the Universe?

The universe is everything we know, from the stars to the galaxies, and beyond. It's an almost unimaginably vast expanse, filled with a myriad of objects that continue to amaze and inspire scientists.

The Big Bang Theory

One of the most significant milestones in our understanding of the universe is the Big Bang Theory. According to this theory, the universe began as an incredibly hot and dense singularity around 13.8 billion years ago, and then expanded rapidly. This expansion continues today, a process called the cosmic microwave background radiation.

The Solar System

Our own universe has a special place for us, as we reside within our solar system. The Sun, our star, lies at the center of the solar system. Around the Sun, we have eight planets, including Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Each of these planets has its unique characteristics, and they orbit the Sun in a path known as the solar orbit.

The Milky Way

Our solar system is a part of a much larger structure, the Milky Way galaxy. This galaxy is a massive collection of billions of stars, along with gas and dust. It is believed to contain about 100 to 400 billion stars, with our Sun being one of them. Our galaxy is shaped like a disk and is approximately 100,000 light years across.

The Scale of the Universe

The scale of the universe is almost beyond comprehension. Consider this:

  • The diameter of an atom is about 0.1 nanometers.
  • The diameter of a human hair is about 100,000 nanometers.
  • A red blood cell is about 10,000 times bigger than an atom, about 1 micrometer in size.
  • The Earth is roughly 12,742 kilometers in diameter, while the Moon is about 3,475 kilometers in diameter.
  • Our Sun is about 1.39 million kilometers across, while Jupiter's diameter is about 139,822 kilometers.
  • The Milky Way is a whopping 100,000 light years in diameter.

Dark Matter and Dark Energy

Dark matter and dark energy are two mysterious components of the universe that are difficult to detect, but their presence is inferred based on their gravitational effects. Dark matter makes up about 27% of the universe, while dark energy accounts for about 73%.

The Cosmic Microwave Background Radiation

The cosmic microwave background radiation is the remains of the Big Bang. First discovered in 1964, it is the most convincing evidence supporting the Big Bang Theory. The radiation is a faint glow that fills the universe, and it is an almost perfect blackbody spectrum.

The History of Astronomy and Space Exploration

Throughout history, humans have been fascinated by the cosmos, and our understanding of the universe has been shaped by the work of astronomers and space explorers. From Galileo Galilei's discovery of planets to the first satellite launch by the Soviet Union, our knowledge of the universe has expanded exponentially. Today, we continue to explore the final frontier, with missions like the James Webb Space Telescope, Mars 2020, and the European Space Agency's Jupiter Icy Moons Explorer.


The first chapter of Class 10 Science introduces us to the universe, its formation, and the fascinating objects that make up our cosmic neighborhood. From the Big Bang to the cosmic microwave background radiation, and from our solar system to the Milky Way, this chapter provides a solid foundation for all future discussions on the mysteries of the universe.


Test your knowledge about the formation of the universe, the Big Bang Theory, the solar system, the Milky Way galaxy, dark matter, cosmic microwave background radiation, and the history of astronomy and space exploration. Dive into the mysteries of the cosmos in this quiz!

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