Samacheer Kalvi Class 4 Science Solutions Term 2 Chapter 2 Water

I. Choose The Correct Answer:

 

Question 1. Water is the most _______ resource on the Earth.
(a) Precious
(b) Solid
(c) Gas
Answer: (a) Precious
In simple words: Water is a very valuable and important resource on Earth. It is essential for all living things.

🎯 Exam Tip: Remember that water is a limited and crucial resource for all life, making it precious.

 

Question 2. Water exists in _______ states.
(a) Two
(b) Three
(c) Four
Answer: (b) Three
In simple words: Water can be found in three forms: solid (like ice), liquid (like tap water), and gas (like steam). These are called its states.

🎯 Exam Tip: Always recall the three main states of matter: solid, liquid, and gas, and how water easily changes between them.

 

Question 3. At temperature below _______ water freezes to form ice.
(a) 10°C
(b) 100°C
(c) 0° C
Answer: (c) 0° C
In simple words: When water gets colder than 0 degrees Celsius, it turns into solid ice. This is the freezing point of water.

🎯 Exam Tip: Know the key temperatures for water's phase changes: 0°C for freezing and 100°C for boiling.

 

Question 4. _______ is the process by which water becomes water vapour.
(a) Condensation
(b) Evaporation
(c) Freezing
Answer: (b) Evaporation
In simple words: Evaporation is when liquid water turns into an invisible gas called water vapour, usually because of heat. This process is how puddles dry up.

🎯 Exam Tip: Clearly understand the definitions of evaporation (liquid to gas) and condensation (gas to liquid) as they are central to the water cycle.

 

Question 5. Which controls the ecological functions of life?
(a) Bicycle
(b) Water cycle
(c) Recycle water
Answer: (b) Water cycle
In simple words: The water cycle plays a very important role in how nature works and helps all living things survive. It moves water around the Earth.

🎯 Exam Tip: Recognize that the water cycle is fundamental to Earth's climate and supports all ecosystems, making it a critical ecological function controller.

II. Fill In The Blanks With Suitable Answer:

 

Question 1. Water is converted into _______ when it is heated. (ice cube/water vapour).
Answer: water vapour
In simple words: When water gets hot, it changes into a gas called water vapour. This is how clouds are formed.

🎯 Exam Tip: Understand that heating adds energy to water, causing it to change from liquid to a gaseous state.

 

Question 2. Water becomes ice on _______ (heating/freezing).
Answer: Freezing
In simple words: Water turns into ice when it gets very cold, a process known as freezing. This is the opposite of melting.

🎯 Exam Tip: Remember that freezing is the process where a liquid turns into a solid, usually due to a drop in temperature.

 

Question 3. Water droplets combine to form _______ (rain/clouds).
Answer: Clouds
In simple words: Tiny water droplets in the air come together to make clouds. These clouds then help to bring rain.

🎯 Exam Tip: Focus on the concept that water vapour condenses to form small droplets, which then group together to become visible clouds.

 

Question 4. Water cycle increases the availability of _______ (water tank/ground water).
Answer: Ground water
In simple words: The water cycle helps to put more water back into the ground. This underground water is very important for us.

🎯 Exam Tip: Think about how precipitation from the water cycle seeps into the ground, replenishing groundwater sources.

 

Question 5. _______ is a type of rainwater harvesting. (Roof top harvesting/Watercycle).
Answer: Roof top harvesting
In simple words: Collecting rainwater from a roof is a smart way to gather water. This method helps save water for later use.

🎯 Exam Tip: Clearly differentiate between the water cycle (a natural process) and rooftop harvesting (a human practice for conservation).

III. Write True Or False:

 

Question 1. Water is a good example for all states of matter.
Answer: True
In simple words: Water shows us how something can be solid, liquid, or gas easily. This makes it a great example to understand different states of matter.

🎯 Exam Tip: Recall that water is unique because its three states (ice, liquid water, steam) are commonly observed on Earth.

 

Question 2. Water cycle controls Earth's temperature.
Answer: True
In simple words: The water cycle helps keep the Earth's temperature stable. It moves heat around the planet, which affects climate.

🎯 Exam Tip: Understand that evaporation absorbs heat and condensation releases it, playing a crucial role in regulating global temperatures.

 

Question 3. Water becoming water vapour on heating is called evaporation.
Answer: True
In simple words: When water gets hot and turns into an invisible gas, that process is known as evaporation. This is a correct definition.

🎯 Exam Tip: Be precise with definitions: evaporation is specifically the change from a liquid to a gas, usually caused by heat.

 

Question 4. 37% of our brain's mass consists of water.
Answer: False
In simple words: Our brain actually has much more water than 37%. It is mostly made of water, closer to 75-80%.

🎯 Exam Tip: Recognize that the human body, including the brain, is composed mostly of water, so a low percentage like 37% would likely be incorrect.

 

Question 5. Roof top harvesting method is used in agriculture field.
Answer: False
In simple words: Rooftop harvesting is mainly for collecting water from buildings, not typically for agriculture fields directly. It gathers water for household use.

🎯 Exam Tip: Distinguish between rooftop harvesting (for urban/residential use) and other rainwater harvesting methods that might be more suitable for agriculture.

IV. Answer Briefly:

 

Question 1. Write the states of water.
Answer: Water naturally comes in three main forms: ice, liquid water, and water vapour. These are often called the states of water. Ice is the solid form, liquid water is the common liquid form, and water vapour is the gaseous form. Water can easily change between these states with temperature changes.
In simple words: Water can be ice (solid), liquid (water), or steam (gas). These are its three natural states.

🎯 Exam Tip: When listing states of matter, always provide a clear example for each state to show full understanding.

 

Question 2. What is freezing?
Answer: Freezing is the process where liquid water turns into solid ice. This happens when the water's temperature drops below 0°C. For example, if you put water in a freezer, it will turn into ice. This change in state is important for many natural processes.
In simple words: Freezing is when water changes from a liquid to a solid (ice) because it gets very cold, below 0°C.

🎯 Exam Tip: Define freezing accurately as a phase change from liquid to solid, and include the critical temperature (0°C for water) for completeness.

 

Question 3. Name the processes involved in water cycle.
Answer: The main processes that make up the water cycle are Evaporation, Condensation, and Precipitation. These three steps constantly move water around the Earth. The water cycle is a continuous process.
In simple words: The water cycle involves evaporation, condensation, and precipitation.

🎯 Exam Tip: When asked to list processes, ensure you include all the primary stages in their correct order if applicable to the cycle.

 

Question 4. Which state government made rain water harvesting as mandatory in the year 2001?
Answer: Tamil Nadu was the first state in India to make rainwater harvesting compulsory in the year 2001. This was a significant step towards water conservation in the region. Other states later followed this example.
In simple words: In 2001, the state of Tamil Nadu made it a rule to collect rainwater.

🎯 Exam Tip: For factual questions like this, remember the specific state and year as key details.

 

Question 5. What is needed to construct a rain water harvesting pit?
Answer: To build a rainwater harvesting pit, you need several materials. These include boulders, gravels, and coarse sand. These materials help in filtering and storing the rainwater effectively. This simple setup allows for groundwater replenishment.
In simple words: You need big stones (boulders), small stones (gravels), and rough sand to build a rainwater harvesting pit.

🎯 Exam Tip: List the essential materials clearly and consider their function in the pit for a comprehensive answer.

V. Answer In Detail:

 

Question 1. What is water cycle? Write any three importances of water cycle.
Answer: The water cycle is a continuous process where water moves around the Earth through different stages like evaporation, condensation, and precipitation. This natural cycle ensures that water is constantly available.
Here are some important reasons why the water cycle is crucial:

• It helps increase the amount of water in the ground, called groundwater.
• It plays a role in controlling the Earth's overall temperature.
• It provides water for all plants and animals, especially humans, helping them survive.
• It constantly recycles and renews the Earth's water supply.

In simple words: The water cycle is how water moves around the Earth. It helps fill underground water, controls Earth's temperature, gives water to living things, and keeps our water supply fresh.

🎯 Exam Tip: When explaining the water cycle, describe its continuous nature and ensure you list at least three distinct and significant benefits.

 

Question 2. What is rain water harvesting? List out the advantages of rain water harvesting.
Answer: Rainwater harvesting is the practice of collecting and storing rainwater to use later. This water can be gathered in natural places like lakes or in man-made tanks. Rooftop harvesting is a common type where rain from building roofs is collected and sent into the ground through pipes. These pipes lead water to a pit filled with gravels and coarse sand, which filters impurities before storing the water underground.
Here are the benefits of rainwater harvesting:

• It helps raise the level of water underground.
• The collected water can be used for farming and agriculture.
• It makes more water available for daily living needs for people and animals.

In simple words: Rainwater harvesting means collecting and storing rainwater for future use. It helps raise groundwater levels, provides water for farms, and increases water supply for everyone.

🎯 Exam Tip: Define rainwater harvesting clearly and then present its advantages using a structured list for better clarity.

V. Colour The Given Picture And Write The Correct Name In The Given Blanks:

 

Question 1. [A diagram illustrating the water cycle with labels for Evaporation, Condensation, Precipitation, and Water storage (Lake, Ocean)]
Answer: This question asks students to colour a picture of the water cycle and fill in the correct names for its parts. This is a practical activity for students to complete on their own, labeling stages like Evaporation, Condensation, Precipitation, and Water storage (Lake, Ocean).
In simple words: This is a fun activity to color the water cycle picture and write the names of its different parts like evaporation and rain. Students should do it themselves.

🎯 Exam Tip: For activity-based questions involving diagrams, ensure students correctly identify and label each stage of the water cycle and understand its flow.

Samacheer Kalvi 4th Science Guide Water Intext Questions And Answers

Let Us Do (Text Book Page No. 69)

 

Question 1. See the given pictures and write down the state of each objects.(Solid, Liquid, Gas)
Answer: The pictures show various objects, each representing a state of matter.
- A bucket of water is in a **Liquid** state.
- Ice cubes are in a **Solid** state.
- A balloon filled with air is in a **Gas** state.
- Water in a pot is in a **Liquid** state.
- Smoke coming from a chimney is in a **Gas** state.
- A toy car is in a **Solid** state.
- Bottles of oil are in a **Liquid** state.
- A chair is in a **Solid** state.
- A glass of juice is in a **Liquid** state.
- A T-shirt is in a **Solid** state.
These examples help us understand the different forms of matter around us.
In simple words: We look at pictures and say if the thing is solid (like a chair), liquid (like water), or gas (like air in a balloon). Most things fit into one of these types.

🎯 Exam Tip: Practice identifying the state of matter (solid, liquid, gas) for common objects based on their appearance and properties.

Let Us Do (Text Book Page No. 70)

 

Question 1. Fill in the boxes given below with correct answers. (Liquid, Solid, Melting, Freezing, Cooling, Heating, Gas)
Answer: The diagram illustrates the changes of state in water.
- **Solid** changes to **Liquid** through **Melting**.
- **Liquid** changes to **Solid** through **Freezing**.
- **Liquid** changes to **Gas** through **Heating**.
- **Gas** changes to **Liquid** through **Cooling**.
These labels correctly show how water changes its form based on temperature changes.
In simple words: The diagram shows how water changes from solid to liquid by melting, liquid to gas by heating, gas back to liquid by cooling, and liquid back to solid by freezing.

🎯 Exam Tip: Be able to label the processes (melting, freezing, heating, cooling) and the states (solid, liquid, gas) correctly in a state change diagram.

 

Question 2. Write any two water bodies in your area
Answer: Two common water bodies found in many areas are a river and a lake. These natural sources are important for various purposes, including providing drinking water and supporting wildlife.
In simple words: A river and a lake are two kinds of water bodies we might find nearby.

🎯 Exam Tip: Think of local examples of water bodies like ponds, rivers, or wells to answer questions about your surroundings.

Try To Answer (Text Book Page No. 71)

 

Question 1. Why water is a good example for all states of matter?
Answer: Water is an excellent example of all states of matter because it is the only natural substance that can easily exist as a solid, liquid, and gas at temperatures we commonly find on Earth. Usually, water is a liquid. However, when it cools to 0°C (32°F), it freezes and becomes solid ice. When liquid water heats up to 100°C (212°F), it boils and turns into steam, which is its gas state. If this steam then touches cool air, it condenses back into liquid water droplets. These droplets can then freeze again to form solid ice. This makes water's changes of state very easy to observe and understand.
In simple words: Water is special because we can easily see it as ice (solid), liquid water, and steam (gas) in our daily lives. It changes states easily with temperature.

🎯 Exam Tip: When explaining why water is a good example, clearly describe its behavior at 0°C (freezing) and 100°C (boiling) and how it transitions between states.

 

Question 2. Which of the following is in liquid state? Rain/Ice/Snow
Answer: Rain is in the liquid state. Ice and snow are both forms of solid water. Rain is what we typically experience as falling liquid water.
In simple words: Out of rain, ice, and snow, only rain is liquid. Ice and snow are solid water.

🎯 Exam Tip: Remember the basic definitions: liquid flows, solid holds shape. Apply this to natural forms of water.

Let Us Do (Text Book Page No. 71)

 

Question 1. Fill water in an ice tray and keep it in the freezer. After few hours, take it out. What happened to the water?
Answer: The water in the ice tray turned into ice, which is the solid state of water. The cold temperature in the freezer caused the water to freeze. This is a common way to make ice cubes at home.
In simple words: The water became ice in the freezer. It changed from liquid to a solid form.

🎯 Exam Tip: Connect everyday experiences like making ice to scientific concepts like freezing and states of matter.

 

Question 2. Now keep this ice tray on a table for some time. What happens to the ice?
Answer: If you leave the ice tray on a table, the ice will absorb heat from the surroundings and melt. It will slowly turn back into liquid water. This shows that melting is the opposite of freezing.
In simple words: The ice will melt and become liquid water again because of the warmer air.

🎯 Exam Tip: Explain that melting occurs due to heat absorption, changing a solid back into a liquid.

 

Question 3. Pour water from the ice tray into a kettle. Ask an elder at your home to heat the kettle and observe the mouth of the kettle when the water starts boiling. What do you see?
Answer: When water in a kettle is heated to boiling, you will see steam coming out of the spout and bubbles forming in the water. This steam is water changing into its gaseous form (water vapour), which happens when enough heat is added. This is a visible sign of evaporation.
In simple words: When the kettle boils, you will see steam come out and bubbles in the water. This means the water is turning into a gas.

🎯 Exam Tip: Describe both the visual cues (steam and bubbles) as evidence of water reaching its boiling point and turning into vapor.

Think And Answer (Text Book Page No. 72)

 

Question 1. What happens to the water in a wet cloth?
Answer: The water in a wet cloth gets evaporated over time. This means the liquid water turns into water vapour and goes into the air. Eventually, all the water leaves the cloth, and it becomes completely dry. This process speeds up if there is wind or heat.
In simple words: The water in a wet cloth dries up because it evaporates into the air.

🎯 Exam Tip: Explain evaporation clearly as the process of liquid water turning into gas and disappearing from the cloth.

Try To Answer (Text Book Page No. 72)

Choose The Correct Answer.

 

Question 1. In the water cycle _______
(a) Only evaporation is involved
(b) Only condensation is involved
(c) Evaporation and condensation are involved
Answer: (c) Evaporation and condensation are involved
In simple words: The water cycle always includes both evaporation (water turning into gas) and condensation (gas turning back into liquid). Both are key parts of the cycle.

🎯 Exam Tip: Emphasize that the water cycle is a continuous loop involving multiple processes, not just a single one.

Try To Answer (Text Book Page No. 72)

 

Question 1. Unscramble the words and fill in the blanks.
Answer:
(a) ondencsaonti: **Condensation**
(b) vaeionorpat: **Evaporation**
(c) ecippitatrino: **Precipitation**
In simple words: The mixed-up words are the main parts of the water cycle: condensation, evaporation, and precipitation.

🎯 Exam Tip: Familiarize yourself with the spelling of key terms related to the water cycle to easily unscramble them.

 

Question 2. Is water cycle important for farming?
Answer: Yes, the water cycle is very important for farming. It provides the necessary rain and groundwater that crops need to grow. Without the water cycle, there would be no consistent water supply for agriculture. It ensures continuous water supply to the soil.
In simple words: Yes, the water cycle is crucial for farming because it brings rain and water for crops to grow.

🎯 Exam Tip: Explain that the water cycle directly provides the precipitation essential for crop irrigation, making it vital for agriculture.

 

Question 3. Why is water cycle important to human?
Answer: The water cycle is very important for humans because it continuously recycles the Earth's water supply. Humans need water for many daily activities like drinking, bathing, cooking, and sanitation. The water cycle ensures that we have a constant supply of fresh water to meet these needs and support our lives. It keeps the planet habitable.
In simple words: The water cycle is important to humans because it keeps giving us fresh water for drinking, washing, and all our daily needs.

🎯 Exam Tip: Focus on how the water cycle provides essential fresh water for human survival and various daily uses.

Try To Answer (Text Book Page No. 74)

 

Question 1. List out some other benefits of rain water harvesting
Answer: Rainwater harvesting offers several benefits beyond just increasing groundwater levels:

• It helps reduce flooding and soil erosion by managing excess rainwater.
• The collected water can be used for many non-drinking purposes, such as bathing, washing clothes, and cleaning.
• It can help plants grow better by providing them with a readily available water source.

This method makes water available for various uses.
In simple words: Rainwater harvesting stops floods, prevents soil from washing away, gives water for washing, and helps plants grow.

🎯 Exam Tip: When listing benefits, consider both environmental impacts (like flood control) and practical uses (like non-potable water).

 

Question 2. Suggest some ideas to save rainwater in your school.
Answer: Here are some ideas to save rainwater at your school:

• Organize awareness programs to teach everyone about the benefits of rainwater harvesting.
• Place large plastic drums around the school to collect excess rainwater that runs off surfaces.
• Install aerators on taps, which can reduce the amount of water flowing from the tap by up to 50%.
• Set up rainwater tanks and connect them to the school's toilets or to the garden for irrigation.

These actions help conserve water and teach students about sustainability.
In simple words: In school, we can teach about rainwater harvesting, collect water in drums, use special tap attachments, and connect tanks to toilets or gardens to save rainwater.

🎯 Exam Tip: Provide a variety of practical and actionable suggestions, covering education, collection, and efficient use of water.

Let Us Do (Text Book Page No. 74)

 

Question 1. Discuss with your friends. Rain water harvesting has an important role to protect our environment.
Answer: Rainwater harvesting plays a vital role in protecting our environment and solving water-related problems. It can be a long-term solution for water shortages, especially in hilly areas where it can provide water for people, animals, and farming. When the monsoon rains are poor, it leads to low crop yields and less food. Animals also suffer from water scarcity during dry seasons. Therefore, rainwater harvesting is an ideal solution for farmers to get a steady water supply, even when monsoon rains are unpredictable.
Additionally, when clean water is scarce, people might have to use polluted water, which can cause water-borne diseases and even increase infant mortality. Collecting rainwater, which is free, helps prevent it from running off and causing soil erosion. Instead, it can be stored to support the main water supply during dry periods.
The importance of rainwater harvesting goes beyond individual families. It benefits whole communities and helps people feel more responsible and aware about caring for our environment. It also recharges groundwater and reduces strain on public water sources.
In simple words: Rainwater harvesting is very important for our environment. It helps solve water problems, provides water for people and farms, prevents diseases from dirty water, and stops soil from washing away. It also makes communities more aware of saving water.

🎯 Exam Tip: For a comprehensive answer, explain multiple environmental and societal benefits of rainwater harvesting, including water availability, health, and conservation.

I. Choose The Best Answer

 

Question 1. Ice is in form of _______ .
(a) Gas
(b) Liquid
(c) Solid
(d) Vapour
Answer: (c) Solid
In simple words: Ice is just water in its frozen, hard form. This is called the solid state of water.

🎯 Exam Tip: Remember that water exists in three main states: solid (ice), liquid (water), and gas (water vapour). Knowing these states helps in understanding many natural processes.

 

Question 2. _______ of our brain's mass consists of water.
(a) 43%
(b) 53%
(c) 63%
(d) 73%
Answer: (d) 73%
In simple words: A big part of our brain is made of water, about 73% of its total weight. This shows how important water is for our body and brain to work well.

🎯 Exam Tip: Facts about the human body's water content often appear in general science questions; remembering key percentages like this can be very useful.

 

Question 3. The Antarctic region has about _______ of the worlds fresh water.
(a) 70%
(b) 60%
(c) 50%
(d) 40%
Answer: (a) 70%
In simple words: Most of the fresh water on Earth is locked up in the Antarctic region as ice. This huge amount is about 70% of all fresh water globally.

🎯 Exam Tip: When studying global resources, understanding where fresh water is stored (like glaciers and ice caps) is crucial for questions about water availability and conservation.

 

Question 4. _______ is the chemical formula of water.
(a) \( \text{H}_2\text{O} \)
(b) HO
(c) \( \text{H}_3\text{O}_2 \)
(d) \( \text{O}_2 \).
Answer: (a) \( \text{H}_2\text{O} \)
In simple words: The chemical name for water is \( \text{H}_2\text{O} \), which means it has two hydrogen atoms and one oxygen atom joined together. This simple formula represents one of the most important substances on Earth.

🎯 Exam Tip: Knowing common chemical formulas like \( \text{H}_2\text{O} \) is fundamental. Practice recognizing the elements and their quantities in simple compounds.

 

II. Fill In The Blanks With Suitable Answer

 

Question 1. Human body consists of _______ of water. Water( 65% / 75%)
Answer: 75%
In simple words: Our bodies are mostly water. About three-quarters of a human body is made up of water.

🎯 Exam Tip: It's good to remember that our bodies need a lot of water to function, so staying hydrated is important.

 

Question 2. _______ is the only way to conserve rain water. (Condensation/Rainwater harvesting)
Answer: Rainwater harvesting
In simple words: Collecting and storing rainwater is a very good way to save water for later use. This is called rainwater harvesting.

🎯 Exam Tip: Rainwater harvesting is an important term in environmental studies; always explain what it means when asked.

 

Question 3. Each day, we lose a little more than a cup of water when we exhale.(inhale/exhale)
Answer: Exhale
In simple words: Every time we breathe out, or exhale, we release a small amount of water vapour. This means we lose some water from our bodies through our breath.

🎯 Exam Tip: This question highlights how our body uses and loses water in various ways, even through breathing. It's a key part of understanding body functions.

 

III. Write True Or False

 

Question 1. The rainwater harvesting was launched by the Tamil Nadu government in 2011.
Answer: False
In simple words: This statement is not true because the rainwater harvesting program in Tamil Nadu was started earlier than 2011.

🎯 Exam Tip: Always double-check dates and years when answering questions about historical events or government initiatives, as they are specific details examiners look for.

 

Question 2. 1 inch of rainfall on a 2000 sq.ft. roof is equal to 4,800 litres of water.
Answer: True
In simple words: If it rains one inch on a roof that is 2000 square feet big, you can collect about 4,800 litres of water. This shows how much water can be collected from a roof.

🎯 Exam Tip: This fact demonstrates the significant potential of rainwater harvesting. Understanding such statistics can strengthen your arguments for water conservation.

 

IV. Answer The Following Questions In One Or Two Sentences

 

Question 1. Where is water available in the liquid state?
Answer: Water in its liquid form is found in many places on Earth. You can find it in oceans, rivers, waterfalls, and lakes. This is the most common form of water we see.
In simple words: Liquid water is found in oceans, rivers, and waterfalls.

🎯 Exam Tip: When listing examples, try to include a variety from different environments to show comprehensive understanding.

 

Question 2. How will you get water vapour from water?
Answer: You can get water vapour from water by heating it. When water gets hot, its temperature rises, and it turns into a white mist. This mist is made of tiny water droplets in the air and is what we call water vapour. For example, when a kettle boils, steam comes out.
In simple words: Heat water, and it will turn into water vapour.

🎯 Exam Tip: Clearly explain the process (heating) and the resulting state (water vapour/mist) to fully answer the question.

 

V. Answer In Detail

 

Question 1. How will you construct a rainwater harvesting pit?
Answer: To build a rainwater harvesting pit at school or home, first you need to dig a pit. You can make it any shape or size, but usually, it is 1 to 2 metres wide and 2 to 3 metres deep. Then, you fill the pit with layers of different materials: put big stones (boulders) at the very bottom, then sand on top of the boulders, and finally, smaller stones (gravels) in the middle layer. This helps filter the water.
In simple words: Dig a pit, then fill it with boulders at the bottom, sand at the top, and gravels in the middle to collect rainwater.

🎯 Exam Tip: When describing a process, use clear steps and specify the materials needed. Remember to explain the purpose of each component (e.g., layers for filtration).