Class 9 Science Chapter 1 MCQs: Exploration – Entering the World of Secondary Science

Science begins with:

विज्ञान की शुरुआत किससे होती है?

• (A) Memorising facts
• (B) Wonder and curiosity
• (C) Using equations
• (D) Building machines

Answer: (B) Wonder and curiosity

Solution: The chapter states that science begins with wonder and curiosity about the world around us.

In secondary science, students learn not only what we know but also:

माध्यमिक विज्ञान में विद्यार्थी केवल यह नहीं सीखते कि हम क्या जानते हैं, बल्कि यह भी सीखते हैं कि:

• (A) Who discovered science
• (B) How we know it
• (C) How to memorize formulas
• (D) How to draw diagrams

Answer: (B) How we know it

Solution: Secondary science focuses on understanding how scientific knowledge is obtained.

The magnifying glass symbol in the textbook represents:

पाठ्यपुस्तक में आवर्धक काँच (Magnifying Glass) का प्रतीक क्या दर्शाता है?

• (A) Direction
• (B) Measurement
• (C) Careful observation
• (D) Experiment

Answer: (C) Careful observation

Solution: The magnifying glass symbolizes careful observation and noticing patterns.

The compass symbol in the textbook represents:

पाठ्यपुस्तक में कम्पास का प्रतीक क्या दर्शाता है?

• (A) Direction in exploration
• (B) Temperature measurement
• (C) Drawing circles
• (D) Gravity

Answer: (A) Direction in exploration

Solution: The compass reminds us that scientific exploration needs direction and purpose.

A scientific model is:

वैज्ञानिक मॉडल क्या होता है?

• (A) An exact copy of reality
• (B) A simplified representation of a real system
• (C) A scientific instrument
• (D) A type of experiment

Answer: (B) A simplified representation of a real system

Solution: Models simplify complex systems so that they can be understood more easily.

Why do scientists use models?

वैज्ञानिक मॉडल का उपयोग क्यों करते हैं?

• (A) To make systems more complex
• (B) To avoid observations
• (C) To understand complex systems easily
• (D) To replace experiments

Answer: (C) To understand complex systems easily

Solution: Models help scientists study complex systems by focusing on important details.

In a simple model of a moving car, the car may be represented as:

चलती हुई कार के सरल मॉडल में कार को किस रूप में दर्शाया जा सकता है?

• (A) A sphere
• (B) A point
• (C) A cube
• (D) A line

Answer: (B) A point

Solution: In physics, a moving car is often represented as a single point.

When studying a falling object, scientists may ignore:

गिरती हुई वस्तु का अध्ययन करते समय वैज्ञानिक किसे अनदेखा कर सकते हैं?

• (A) Gravity
• (B) Mass
• (C) Air resistance
• (D) Motion

Answer: (C) Air resistance

Solution: Air resistance is often ignored in simple models to focus on gravity.

In the cricket ball example, which factor is most important?

क्रिकेट गेंद के उदाहरण में कौन-सा कारक सबसे महत्वपूर्ण है?

• (A) Colour of the ball
• (B) Brand of the bat
• (C) Speed and direction of the ball
• (D) Grass on the field

Answer: (C) Speed and direction of the ball

Solution: The speed and direction of the ball determine whether it crosses the boundary.

Which of the following can be ignored in a simple cricket shot model?

सरल क्रिकेट शॉट मॉडल में निम्नलिखित में से किसे अनदेखा किया जा सकता है?

• (A) Mass of the ball
• (B) Speed of the ball
• (C) Direction of the ball
• (D) Colour of the ball

Answer: (D) Colour of the ball

Solution: The colour of the ball does not significantly affect its motion.

Scientific terms are used carefully because they must be:

वैज्ञानिक शब्दों का उपयोग सावधानी से किया जाता है क्योंकि उन्हें होना चाहिए:

• (A) Interesting
• (B) Short
• (C) Clear and unambiguous
• (D) Difficult

Answer: (C) Clear and unambiguous

Solution: Scientific language must be precise so that ideas are communicated clearly.

Which of the following is a symbol for force?

निम्नलिखित में से बल (Force) का प्रतीक कौन-सा है?

• (A) m
• (B) v
• (C) F
• (D) I

Answer: (C) F

Solution: The symbol F is commonly used to represent force.

Which symbol represents electric current?

विद्युत धारा (Electric Current) का प्रतीक कौन-सा है?

• (A) I
• (B) F
• (C) m
• (D) v

Answer: (A) I

Solution: Electric current is represented by the symbol I.

Mathematics in science is mainly used to:

विज्ञान में गणित का मुख्य उपयोग किस लिए किया जाता है?

• (A) Decorate diagrams
• (B) Think clearly and express relationships
• (C) Replace observations
• (D) Avoid experiments

Answer: (B) Think clearly and express relationships

Solution: Mathematics helps express relationships between quantities clearly.

An equation in science is:

विज्ञान में समीकरण क्या होता है?

• (A) Only a calculation tool
• (B) A type of experiment
• (C) A statement showing relationships between quantities
• (D) A diagram

Answer: (C) A statement showing relationships between quantities

Solution: An equation describes how different quantities are related.

Before using an equation, students should first:

किसी समीकरण का उपयोग करने से पहले विद्यार्थियों को सबसे पहले क्या करना चाहिए?

• (A) Memorise it
• (B) Understand the situation
• (C) Ignore quantities
• (D) Calculate immediately

Answer: (B) Understand the situation

Solution: Understanding the situation is the first step before applying equations.

Which quantity is represented by the symbol m?

प्रतीक m किस राशि को दर्शाता है?

• (A) Force
• (B) Velocity
• (C) Mass
• (D) Current

Answer: (C) Mass

Solution: The symbol m is used to represent mass.

Which quantity is represented by the symbol v?

प्रतीक v किस राशि को दर्शाता है?

• (A) Velocity
• (B) Mass
• (C) Force
• (D) Current

Answer: (A) Velocity

Solution: The symbol v is used to represent velocity.

Scientific ideas are tested through:

वैज्ञानिक विचारों की जाँच किसके माध्यम से की जाती है?

• (A) Experiments
• (B) Stories
• (C) Guesses
• (D) Opinions

Answer: (A) Experiments

Solution: Experiments are used to test scientific ideas and evidence.

Science helps us understand:

विज्ञान हमें किसे समझने में सहायता करता है?

• (A) Only nature
• (B) Only technology
• (C) Nature, technology and our place within them
• (D) Only living organisms

Answer: (C) Nature, technology and our place within them

Solution: Science helps us make sense of nature, technology, and our role in the world.

Who is the scientist mentioned in the 'Meet a Scientist' section?

'Meet a Scientist' अनुभाग में किस वैज्ञानिक का उल्लेख किया गया है?

• (A) C. V. Raman
• (B) Albert Einstein
• (C) Meghnad Saha
• (D) Isaac Newton

Answer: (C) Meghnad Saha

Solution: The section discusses physicist Meghnad Saha and his work on stars.

Meghnad Saha studied the light from:

मेघनाद साहा ने किसके प्रकाश का अध्ययन किया?

• (A) Planets
• (B) Stars
• (C) Moon
• (D) Comets

Answer: (B) Stars

Solution: Meghnad Saha studied the light coming from stars.

While studying stars, Meghnad Saha treated stellar matter as:

तारों का अध्ययन करते समय मेघनाद साहा ने तारकीय पदार्थ को किस रूप में माना?

• (A) A solid
• (B) A liquid
• (C) A hot gas
• (D) Plasma only

Answer: (C) A hot gas

Solution: He simplified the problem by treating the matter in stars as a hot gas.

Meghnad Saha mainly focused on:

मेघनाद साहा मुख्य रूप से किस पर ध्यान केंद्रित करते थे?

• (A) Colour, shape and size
• (B) Temperature, pressure and ion formation
• (C) Mass and volume only
• (D) Distance and speed

Answer: (B) Temperature, pressure and ion formation

Solution: He focused on temperature, pressure and the formation of ions.

Meghnad Saha's work helped explain the relationship between a star's colour and its:

मेघनाद साहा के कार्य ने तारे के रंग और उसके किस गुण के बीच संबंध को समझाने में सहायता की?

• (A) Mass
• (B) Age
• (C) Temperature
• (D) Distance

Answer: (C) Temperature

Solution: He showed that the colour of stars is closely related to their temperature.

The symbol used for the speed of light is:

प्रकाश की गति के लिए कौन-सा प्रतीक उपयोग किया जाता है?

• (A) s
• (B) l
• (C) c
• (D) v

Answer: (C) c

Solution: The speed of light is represented by the symbol c.

The symbol 'c' comes from the Latin word:

'c' प्रतीक किस लैटिन शब्द से लिया गया है?

• (A) celeritas
• (B) calor
• (C) corpus
• (D) centrum

Answer: (A) celeritas

Solution: The symbol c comes from the Latin word 'celeritas', meaning speed.

The Latin word 'celeritas' means:

लैटिन शब्द 'celeritas' का अर्थ क्या है?

• (A) Light
• (B) Motion
• (C) Speed
• (D) Energy

Answer: (C) Speed

Solution: Celeritas is a Latin word meaning speed.

The speed of light is defined to be exactly:

प्रकाश की गति को ठीक कितना परिभाषित किया गया है?

• (A) 299792458 m/s
• (B) 300000000 m/s
• (C) 29979245.8 m/s
• (D) 299792458 km/s

Answer: (A) 299792458 m/s

Solution: The speed of light is exactly 299792458 metres per second.

In the airplane fuel incident, the problem occurred because of:

हवाई जहाज ईंधन घटना में समस्या किस कारण हुई?

• (A) Engine failure
• (B) Bad weather
• (C) Mix-up of units
• (D) Pilot error

Answer: (C) Mix-up of units

Solution: The incident happened because different units were used incorrectly.

The aircraft required a total of:

विमान को कुल कितने ईंधन की आवश्यकता थी?

• (A) 22,300 kg fuel
• (B) 15,000 kg fuel
• (C) 22,300 litres fuel
• (D) 10,000 kg fuel

Answer: (A) 22,300 kg fuel

Solution: The flight required a total of 22,300 kg of fuel.

The aircraft was short of approximately:

विमान में लगभग कितने लीटर ईंधन की कमी थी?

• (A) 5,000 litres
• (B) 10,000 litres
• (C) 15,000 litres
• (D) 20,000 litres

Answer: (C) 15,000 litres

Solution: The aircraft was about 15,000 litres short of fuel.

The airplane managed to:

विमान अंततः क्या करने में सफल रहा?

• (A) Return to the airport
• (B) Glide to an emergency landing
• (C) Continue its journey
• (D) Land on water

Answer: (B) Glide to an emergency landing

Solution: Despite running out of fuel, the aircraft glided to an emergency landing.

Using standard SI units helps to avoid:

मानक SI इकाइयों का उपयोग किससे बचने में सहायता करता है?

• (A) Observations
• (B) Experiments
• (C) Conversions and errors
• (D) Measurements

Answer: (C) Conversions and errors

Solution: Using SI units reduces conversion mistakes and errors.

Why is a kilogram used everywhere?

किलोग्राम का उपयोग हर जगह क्यों किया जाता है?

• (A) It is easier to pronounce
• (B) It is a standard international unit
• (C) It is lighter than other units
• (D) It is used only in science

Answer: (B) It is a standard international unit

Solution: Kilogram is an internationally accepted standard unit of mass.

Standard units are based on:

मानक इकाइयाँ किस पर आधारित होती हैं?

• (A) Local customs
• (B) Personal opinions
• (C) International agreements
• (D) Market prices

Answer: (C) International agreements

Solution: Measurements are based on internationally agreed standards.

Standard units ensure fairness in:

मानक इकाइयाँ किसमें निष्पक्षता सुनिश्चित करती हैं?

• (A) Games only
• (B) Trade and daily life
• (C) School exams only
• (D) Transportation only

Answer: (B) Trade and daily life

Solution: Standard units help maintain fairness in trade and everyday transactions.

When buying vegetables, a kilogram should mean:

सब्जियाँ खरीदते समय एक किलोग्राम का अर्थ क्या होना चाहिए?

• (A) Different amounts in different places
• (B) The same amount everywhere
• (C) Any convenient amount
• (D) A local measurement

Answer: (B) The same amount everywhere

Solution: A kilogram should represent the same amount everywhere.

Scientific symbols are often chosen based on:

वैज्ञानिक प्रतीकों का चयन प्रायः किस आधार पर किया जाता है?

• (A) Convenient abbreviations only
• (B) History and international agreements
• (C) Personal preference
• (D) Alphabetical order

Answer: (B) History and international agreements

Solution: Many scientific symbols come from historical usage and international conventions.

The main lesson from the airplane fuel incident is that:

हवाई जहाज ईंधन घटना से मुख्य शिक्षा क्या मिलती है?

• (A) Airplanes need more fuel
• (B) Pilots should check weather reports
• (C) Correct units are essential in science and technology
• (D) Fuel should be measured in litres only

Answer: (C) Correct units are essential in science and technology

Solution: Using correct and standard units is essential to prevent serious errors.

A scientific law mainly describes:

वैज्ञानिक नियम मुख्य रूप से क्या वर्णन करता है?

• (A) Why a phenomenon occurs
• (B) A regular pattern in nature
• (C) A scientific instrument
• (D) A laboratory procedure

Answer: (B) A regular pattern in nature

Solution: A scientific law describes a regular pattern or relationship observed in nature.

Newton's laws of motion are examples of:

न्यूटन के गति के नियम किसके उदाहरण हैं?

• (A) Theories
• (B) Principles
• (C) Laws
• (D) Models

Answer: (C) Laws

Solution: Newton's laws of motion describe patterns in motion.

A scientific theory mainly explains:

वैज्ञानिक सिद्धांत मुख्य रूप से क्या समझाता है?

• (A) Why patterns occur
• (B) Only observations
• (C) Laboratory equipment
• (D) Units of measurement

Answer: (A) Why patterns occur

Solution: A theory explains why observed patterns occur.

Which theory explains how molecules are formed?

कौन-सा सिद्धांत बताता है कि अणु कैसे बनते हैं?

• (A) Cell Theory
• (B) Atomic Theory
• (C) Evolution Theory
• (D) Germ Theory

Answer: (B) Atomic Theory

Solution: Atomic Theory explains how atoms combine to form molecules.

In science, a theory is:

विज्ञान में सिद्धांत क्या होता है?

• (A) A guess
• (B) An opinion
• (C) A well-tested explanation
• (D) A prediction

Answer: (C) A well-tested explanation

Solution: Scientific theories are based on evidence and extensive testing.

A principle is:

सिद्धांत (Principle) क्या है?

• (A) A broad scientific idea
• (B) A measuring instrument
• (C) A mathematical symbol
• (D) A unit

Answer: (A) A broad scientific idea

Solution: Principles are broad ideas that help explain situations.

Which principle is used while climbing stairs?

सीढ़ियाँ चढ़ते समय कौन-सा सिद्धांत लागू होता है?

• (A) Archimedes' Principle
• (B) Conservation of Energy
• (C) Pascal's Principle
• (D) Bernoulli's Principle

Answer: (B) Conservation of Energy

Solution: Energy changes form while climbing stairs, demonstrating conservation of energy.

One of the greatest strengths of science is its ability to:

विज्ञान की सबसे बड़ी शक्तियों में से एक क्या है?

• (A) Memorize facts
• (B) Make predictions
• (C) Avoid experiments
• (D) Replace observations

Answer: (B) Make predictions

Solution: Science can predict future outcomes using evidence and models.

Scientific predictions are based on:

वैज्ञानिक पूर्वानुमान किस पर आधारित होते हैं?

• (A) Luck
• (B) Guesses
• (C) Evidence and careful reasoning
• (D) Opinions

Answer: (C) Evidence and careful reasoning

Solution: Predictions are based on evidence, observations and scientific understanding.

Which of the following is useful for testing a rain prediction scientifically?

वर्षा के पूर्वानुमान को वैज्ञानिक रूप से जाँचने के लिए निम्न में से क्या उपयोगी है?

• (A) Clouds look nice
• (B) Humidity measurements
• (C) Personal belief
• (D) Random guessing

Answer: (B) Humidity measurements

Solution: Humidity is measurable data that helps test weather predictions.

Weather forecasts depend on:

मौसम पूर्वानुमान किन पर निर्भर करता है?

• (A) Temperature, pressure, humidity and wind
• (B) Only temperature
• (C) Only humidity
• (D) Only wind

Answer: (A) Temperature, pressure, humidity and wind

Solution: Many factors together affect weather forecasts.

Why are long-term weather forecasts less certain?

दीर्घकालिक मौसम पूर्वानुमान कम निश्चित क्यों होते हैं?

• (A) Weather never changes
• (B) Small changes can grow over time
• (C) Scientists do not measure weather
• (D) Forecasts are guesses

Answer: (B) Small changes can grow over time

Solution: Tiny differences in conditions can lead to very different future outcomes.

When predictions do not match observations, scientists:

जब पूर्वानुमान अवलोकनों से मेल नहीं खाते, तो वैज्ञानिक क्या करते हैं?

• (A) Ignore the evidence
• (B) Check assumptions and improve models
• (C) Stop experimenting
• (D) Reject science

Answer: (B) Check assumptions and improve models

Solution: Scientists re-examine assumptions, measurements and models.

Scientific theories can change when:

वैज्ञानिक सिद्धांत कब बदल सकते हैं?

• (A) New evidence becomes available
• (B) People dislike them
• (C) A scientist retires
• (D) A new textbook is printed

Answer: (A) New evidence becomes available

Solution: Science updates theories when supported by new evidence.

No scientific theory is:

कोई भी वैज्ञानिक सिद्धांत क्या नहीं होता?

• (A) Useful
• (B) Evidence-based
• (C) Final and beyond question
• (D) Testable

Answer: (C) Final and beyond question

Solution: Scientific theories remain open to revision and improvement.

According to science, an eclipse is mainly:

विज्ञान के अनुसार ग्रहण मुख्य रूप से क्या है?

• (A) A chemical reaction
• (B) A biological process
• (C) A play of shadows
• (D) A weather event

Answer: (C) A play of shadows

Solution: An eclipse is simply caused by the shadow of one celestial body falling on another.

Why should viral claims be examined scientifically?

वायरल दावों की वैज्ञानिक जाँच क्यों करनी चाहिए?

• (A) To increase popularity
• (B) To find evidence-based truth
• (C) To support rumours
• (D) To avoid observations

Answer: (B) To find evidence-based truth

Solution: Scientific examination helps determine whether a claim is supported by evidence.

Which of the following is NOT a scientific question about eclipses?

निम्नलिखित में से कौन-सा ग्रहण के बारे में वैज्ञानिक प्रश्न नहीं है?

• (A) Does temperature change significantly?
• (B) Does food spoil in shadow?
• (C) Is there scientific evidence?
• (D) Is the eclipse unlucky?

Answer: (D) Is the eclipse unlucky?

Solution: Science relies on measurable evidence, not superstition.

Estimation means finding:

अनुमान (Estimation) का अर्थ है:

• (A) An exact answer
• (B) An approximate answer
• (C) A wrong answer
• (D) A mathematical formula

Answer: (B) An approximate answer

Solution: Estimation provides a reasonable approximate value.

Which is the first step in solving a scientific problem?

वैज्ञानिक समस्या को हल करने का पहला चरण क्या है?

• (A) Calculate immediately
• (B) Memorize formulas
• (C) Understand the situation
• (D) Guess the answer

Answer: (C) Understand the situation

Solution: Understanding the situation is the first step before calculations.

Science values _____ more than accurate calculations.

विज्ञान सटीक गणनाओं से अधिक _____ को महत्व देता है।

• (A) Luck
• (B) Careful reasoning
• (C) Speed
• (D) Opinions

Answer: (B) Careful reasoning

Solution: The chapter emphasizes careful reasoning over exact calculations.

The rice estimation example teaches:

चावल अनुमान उदाहरण हमें क्या सिखाता है?

• (A) Exact answers are always needed
• (B) Approximate reasoning is useful
• (C) Rice contains no calories
• (D) Science avoids calculations

Answer: (B) Approximate reasoning is useful

Solution: The purpose is to learn estimation and reasonable thinking.

Understanding how a mask works requires knowledge from:

मास्क कैसे कार्य करता है, इसे समझने के लिए किस ज्ञान की आवश्यकता होती है?

• (A) Only Physics
• (B) Only Biology
• (C) Only Chemistry
• (D) Several branches of science

Answer: (D) Several branches of science

Solution: Physics, Chemistry, Biology and Mathematics all contribute.

Which branch of science helps explain virus behaviour in masks?

मास्क में वायरस के व्यवहार को समझाने में कौन-सी विज्ञान शाखा सहायता करती है?

• (A) Biology
• (B) Geology
• (C) Astronomy
• (D) Meteorology

Answer: (A) Biology

Solution: Biology studies living organisms and viruses.

At rest, a person typically takes about:

आराम की अवस्था में एक व्यक्ति लगभग कितनी साँसें प्रति मिनट लेता है?

• (A) 2–5
• (B) 12–15
• (C) 30–40
• (D) 50–60

Answer: (B) 12–15

Solution: An average resting person takes about 12–15 breaths per minute.

Approximately how many breaths does a person take in a day?

एक व्यक्ति एक दिन में लगभग कितनी साँसें लेता है?

• (A) 2,000
• (B) 5,000
• (C) 20,000
• (D) 50,000

Answer: (C) 20,000

Solution: A person takes approximately 20,000 breaths per day.

The estimated volume of one normal breath is about:

एक सामान्य साँस का अनुमानित आयतन कितना होता है?

• (A) 0.5 litre
• (B) 5 litres
• (C) 10 litres
• (D) 20 litres

Answer: (A) 0.5 litre

Solution: One breath is estimated to contain about 0.5 litre of air.

A person breathes approximately how much air in one day?

एक व्यक्ति एक दिन में लगभग कितनी वायु लेता है?

• (A) 100 litres
• (B) 500 litres
• (C) 1,000 litres
• (D) 10,000 litres

Answer: (D) 10,000 litres

Solution: The chapter estimates about 10,000 litres of air per day.

Using different methods to estimate the same quantity helps:

एक ही राशि का अलग-अलग तरीकों से अनुमान लगाने से क्या लाभ होता है?

• (A) Increase confusion
• (B) Verify whether the estimate is reasonable
• (C) Avoid calculations
• (D) Produce exact answers

Answer: (B) Verify whether the estimate is reasonable

Solution: Different estimates can be compared to check reasonableness.

Interdisciplinary science means:

अंतर्विषयक विज्ञान (Interdisciplinary Science) का अर्थ क्या है?

• (A) Studying only one subject
• (B) Using multiple branches of science together
• (C) Ignoring mathematics
• (D) Avoiding experiments

Answer: (B) Using multiple branches of science together

Solution: Many real-life problems require concepts from different scientific fields.