This MCQ module is based on: Solubility, Floating, Density and ORS
Solubility, Floating, Density and ORS
6.3.4 Solubility — Which Things Dissolve in Water?
Drop a spoon of sugar into a glass of water and stir. After a few seconds, the sugar disappears! But if you drop a spoon of sand into water and stir, the sand just settles at the bottom. This "disappearing trick" has a name — it is called solubility.
You need: 6 clean glasses with water, small quantities of: sugar, salt, sand, chalk powder, oil, honey. A spoon to stir.
- Put one spoon of each substance into a separate glass of water.
- Stir for 30 seconds. Wait 1 minute.
- Observe: did the substance dissolve completely, settle at the bottom, or float on top?
Liquids in Liquids — Miscible or Immiscible?
Two liquids that mix completely are called miscible (e.g., milk + water, honey + water). Two liquids that refuse to mix are called immiscible (e.g., oil + water, kerosene + water). Next time you see salad dressing settle into layers, you know why!
⚕️ A Life-Saving Use of Solubility — Making ORS
🥤 How to Make ORS at Home
All three ingredients dissolve completely in water — that's why we can use this property of solubility to save a life.
Method: Add salt and sugar to the cool boiled water. Stir until fully dissolved. Sip small amounts regularly. Ready-made WHO ORS packets are also easily available at any chemist shop — just open the packet and mix with 1 litre of water.
Why it works: Water replaces lost body water, salt replaces lost body salts, and sugar gives the body quick energy and helps it absorb water faster.
Gases Dissolve in Water Too!
Water doesn't only dissolve solids and liquids — it also dissolves gases. A little oxygen is always dissolved in pond, river and sea water. Fish, crabs and water plants breathe this dissolved oxygen through their gills and leaves. Without it, aquatic life would die in hours!
Open a bottle of cold cola or soda and you hear psshh — lots of tiny bubbles escape. That's carbon dioxide, a gas dissolved under pressure during bottling. When you open the bottle, pressure drops and CO₂ rushes out — that's the fizz!
6.3.5 How Heavy or Light — Density
Pick up a small stone and a small piece of sponge of about the same size. The stone feels much heavier. Why? Both objects take the same space, but the stone packs more matter into that space. This "packed-ness" is called density.
You need: three identical paper cups, water, dry sand, and air (yes — air!). A simple balance or your hand to compare weight.
- Fill Cup 1 with water to the brim.
- Fill Cup 2 with dry sand to the same level.
- Leave Cup 3 empty — it is filled with air.
- Hold all three cups one by one. Which is heaviest? Lightest?
6.3.6 Floating and Sinking — The Density Game
Put a small stone in water → it sinks. Put a dry piece of wood → it floats. The rule is simple:
Shape Can Change the Game!
This is the fun part. Take a lump of clay and drop it into water — it sinks straight away (clay is denser than water). But if you squash that same lump of clay into the shape of a boat with a hollow inside, it floats! How?
The secret: a boat-shape encloses a lot of air. The total (clay + air) takes up a much bigger volume now, while the mass is almost the same. So the overall density of the boat is less than water — and it floats! This is exactly how huge steel ships carrying thousands of tonnes float on the sea, even though solid steel sinks.
You need: a bucket of water and these items — iron nail, plastic spoon, small stone, piece of dry wood, coin, sponge, rubber band, a small piece of thermocol, a dry leaf.
- Before dropping, predict each item: will it float or sink?
- Drop each item in the bucket and observe.
- Fill Table 6.2 in your notebook with Predict vs Actual results.
Interactive: Float or Sink? L3
Pick an object, predict Float or Sink, then press Drop in water and watch!
Competency-Based Questions
Q1. What is the drink Aarav's grandmother prepared called? L1
Q2. Why is sugar added to ORS? L2
Q3. Give two examples each of soluble and insoluble substances in water. L1
Q4. A lump of clay sinks in water, but the same clay moulded into a boat floats. Why? L4
Q5. Fish cannot survive in very dirty water. What property of water is responsible for this? L4
Assertion – Reason
Assertion (A): A big iron ship floats on water though iron is denser than water.
Reason (R): The ship's hollow shape traps a lot of air, lowering its overall density below that of water.
Assertion (A): ORS helps treat dehydration from diarrhoea.
Reason (R): ORS replaces water, salts and provides glucose that the body has lost.
Assertion (A): Oil poured into water settles at the bottom.
Reason (R): Oil is denser than water.
Frequently Asked Questions — Solubility, Floating, Density and ORS
What does the topic 'Solubility, Floating, Density and ORS' cover in Class 6 Science?
The topic 'Solubility, Floating, Density and ORS' is part of NCERT Class 6 Science Chapter 6 — Materials Around Us. It covers the key ideas of solubility, soluble, insoluble, floating, sinking, density, ORS, oral rehydration solution, explained through everyday examples, labelled diagrams and hands-on activities from the NCERT Curiosity textbook. Class 6 students learn simple definitions, see why each idea matters in daily life, and try short experiments and observations. The lesson uses easy language, colourful pictures and small questions so that young learners build a strong base for higher classes and for competency-based questions in CBSE school tests.
Why is 'Solubility, Floating, Density and ORS' important for Class 6 NCERT Science?
'Solubility, Floating, Density and ORS' is important because it builds the first ideas of science that Class 6 students will use again in Class 7, 8 and beyond. NCERT Chapter 6 — Materials Around Us — introduces solubility and connects it to things children already see at home, at school and in nature. Learning this topic helps students ask better questions, understand simple news about science, and score well in CBSE tests that use competency-based questions. The chapter also supports NEP 2020 by encouraging curiosity, observation and learning by doing rather than only reading and memorising.
What are the key ideas students should remember from Solubility, Floating, Density and ORS?
The key ideas in 'Solubility, Floating, Density and ORS' for Class 6 Science are: solubility, soluble, insoluble, floating, sinking, density, ORS, oral rehydration solution. Students should be able to say each term in their own words, give one or two easy examples from daily life, and draw a small labelled diagram where needed. A good way to revise is to make flashcards, write a short note in the science notebook, and solve the NCERT in-text and exercise questions of Chapter 6. Linking every idea to something seen at home or school — in the kitchen, garden, playground or sky — makes these ideas easy to remember for unit tests and the annual CBSE examination.
How is Solubility, Floating, Density and ORS taught using activities in NCERT Curiosity Class 6?
NCERT Curiosity Class 6 Science teaches 'Solubility, Floating, Density and ORS' through an inquiry-based approach using Predict–Observe–Explain activities. Students first make a guess, then try a small experiment with safe, easily available materials, and finally explain what happened and why. This matches the NEP 2020 focus on learning by doing. For Chapter 6 — Materials Around Us — the textbook has hands-on tasks, labelled pictures and thinking questions built for Bloom's Taxonomy Levels 1 to 6. Teachers use these activities, along with competency-based questions (CBQs) and assertion–reason items, to check real understanding instead of only rote learning.
What real-life examples of solubility can Class 6 students see at home?
Class 6 students can see solubility at home in many simple ways linked to 'Solubility, Floating, Density and ORS'. Kitchens, school bags, playgrounds, the garden and the night sky are full of examples that match NCERT Chapter 6 — Materials Around Us. For example, students can look at food labels, watch changes while cooking, try safe activities with water, magnets or shadows, and observe the Sun, Moon and weather each day. Keeping a small science diary — with the date, what was observed and a quick drawing — turns daily life into a mini science lab. These real-life links make concepts easy to remember and help in answering competency-based questions in CBSE Class 6 Science.
How does 'Solubility, Floating, Density and ORS' connect to other chapters of Class 6 Science?
'Solubility, Floating, Density and ORS' connects to many other chapters in NCERT Class 6 Science Curiosity. The ideas of solubility come back when students study related topics like diversity in the living world, food, magnets, measurement, materials, temperature, water, separation, habitats, natural resources and the solar system. For example, what students learn here helps them build mental pictures for later chapters and for Class 7 and Class 8 Science. Teachers often ask cross-chapter questions in CBSE exams to check if students can use what they learned in Chapter 6 — Materials Around Us — in new situations. This linked approach matches the NEP 2020 and NCF 2023 focus on holistic, competency-based learning.