Samacheer Kalvi Class 6 Science Solutions Term 3 Chapter 3 Chemistry in Everyday Life

Tamilnadu Samacheer Kalvi 6th Science Solutions Term 3 Chapter 3 Chemistry in Everyday Life

Samacheer Kalvi 6th Science Chemistry in Everyday Life Text Book Back Questions and Answers

I. Choose the correct Answer:

Question 1. Soaps were originally made from .........
(a) proteins
(b) animal fats and vegetable oils
(c) chemicals extracted from the soil
(d) foam booster
Answer: (b) animal fats and vegetable oils
In simple words: Soaps were first made using animal fats and oils from plants. These natural ingredients were combined to create the early forms of soap.

🎯 Exam Tip: Remember that traditional soap making (saponification) involves fats/oils reacting with a strong alkali.

Question 2. The saponification of a fat or oil is done using ________ solution for hot process.
(a) Potassium hydroxide
(b) Sodium hydroxide
(c) Hydrochloric acid
(d) Sodium chloride
Answer: (b) Sodium hydroxide
In simple words: For making soap using the hot process, sodium hydroxide (also called lye) is mixed with fats or oils. This chemical reaction creates soap.

🎯 Exam Tip: Distinguish between sodium hydroxide (for hard soaps) and potassium hydroxide (for soft soaps/liquid soaps).

Question 3. Gypsum is added to the cement for .........
(a) fast setting
(b) delayed setting
(c) hardening
(d) making paste
Answer: (b) delayed setting
In simple words: Gypsum is put into cement to make it dry slower. This gives workers more time to use the cement before it becomes hard.

🎯 Exam Tip: The key role of gypsum in cement is to control the rate of hydration and setting, preventing it from hardening too quickly.

Question 4. Phenol is .........
(a) carbolic acid
(b) acetic acid
(c) benzoic acid
(d) hydrochloric acid
Answer: (a) carbolic acid
In simple words: Phenol is also known by another common name, carbolic acid. It is an organic chemical compound.

🎯 Exam Tip: Always remember common names for chemicals, as they are often used interchangeably with scientific names.

Question 5. Natural adhesives are made from .........
(a) Protein
(b) fat
(c) starch
(d) vitamins
Answer: (c) starch
In simple words: Natural glues, or adhesives, are often made from starch, which comes from plants. This makes them safe and easy to use.

🎯 Exam Tip: Natural adhesives like starch-based glues are environmentally friendly and biodegradable.

II. Fill in the Blanks

Question 1. ........... gas causes tears in our eyes while cutting onions.
Answer: Propane Thiol Oxide
In simple words: When you cut onions, a gas called propane thiol oxide is released into the air, which makes your eyes water. This gas acts as a defense mechanism for the plant.

🎯 Exam Tip: Knowing the specific chemical compound responsible for common phenomena like onion tears shows a deeper understanding of chemistry.

Question 2. Water, coconut oil and ........... are necessary for soap preparation.
Answer: NaOH
In simple words: To make soap, you need water, coconut oil, and NaOH, which is sodium hydroxide. The sodium hydroxide reacts with the oil to form soap.

🎯 Exam Tip: NaOH (sodium hydroxide) is a crucial ingredient in the saponification process for making solid soaps.

Question 3. ........... is called a farmer's best friend.
Answer: Earthworm
In simple words: Earthworms are known as a farmer's best friend because they help make the soil healthy and rich. They dig tunnels and eat organic matter, which improves soil quality.

🎯 Exam Tip: Earthworms are vital for soil aeration and nutrient cycling, making them invaluable in agriculture.

Question 4. ........... fertilizer is ecofriendly.
Answer: Artificial
In simple words: Artificial fertilizers are not typically eco-friendly as they can harm the environment if not used carefully. Organic fertilizers are generally considered more eco-friendly.

🎯 Exam Tip: Understand the difference between artificial (synthetic) and organic fertilizers and their environmental impacts.

Question 5. ........... is an example for natural adhesive.
Answer: Starch
In simple words: Starch is a great example of a natural sticky substance used as an adhesive. It is often found in plants like potatoes and corn.

🎯 Exam Tip: Starch-based adhesives are biodegradable and are used in various everyday applications, such as paper gluing.

III. True or False. If False, give the correct statement.

Question 1. Concentrated phenol is used as a disinfectant.
Answer: False. Low concentrated Phenol is used as a disinfectant.
In simple words: It is false because only weak solutions of phenol are used to clean things and kill germs. Strong phenol is too harmful.

🎯 Exam Tip: Always note the concentration when discussing the uses of chemicals like phenol, as higher concentrations can be toxic.

Question 2. Gypsum is largely used in medical industries.
Answer: False. Epsom salt is largely used in medical industry.
In simple words: This is false because Epsom salt is mostly used in medicine, not gypsum. Gypsum is more commonly used in building and construction.

🎯 Exam Tip: Differentiate between gypsum (calcium sulfate dihydrate) and Epsom salt (magnesium sulfate), as they have distinct uses.

Question 3. Plaster of Paris is obtained from heating gypsum.
Answer: True.
In simple words: This statement is true because Plaster of Paris is made by heating gypsum, which removes some water from it. This process changes its chemical structure.

🎯 Exam Tip: Understand the conversion of gypsum to Plaster of Paris (POP) and how this process changes its properties, making it useful for casts.

Question 4. Adhesives are the substances used to separate the components.
Answer: False. Adhesives are substances that are used to join two (or) more components.
In simple words: This is false; glues are used to stick things together, not pull them apart. They form a bond between different materials.

🎯 Exam Tip: Clearly define the function of adhesives as bonding agents that hold materials together.

Question 5. NPK are the primary nutrients for plants.
Answer: True.
In simple words: This statement is true because Nitrogen (N), Phosphorus (P), and Potassium (K) are the three most important nutrients plants need to grow well. They play vital roles in plant health.

🎯 Exam Tip: Always remember NPK as the acronym for the main macronutrients essential for plant growth and development.

IV. Match the following:

🎯 Exam Tip: For matching questions, connect each item to its most defining characteristic or chemical compound.

V. Arrange the following statements in the correct sequence:

Question 1. Pour that solution into an empty matchbox, soap can be obtained after drying.
Question 2. Take the necessary quantity of water in a jar.
Question 3. Then add coconut oil drop by drop and stir it well.
Question 4. Add concentrated sodium hydroxide in the jar and allow it to cool.
Question 5. Try this soap to wash your handkerchief.
Question 6. Cover your work area with old newspaper.
Answer:
1. Cover your work area with old newspaper.
2. Take the necessary quantity of water in a jar.
3. Add concentrated sodium hydroxide in the jar and allow it to cool.
4. Then add coconut oil drop by drop and stir it well.
5. Pour that solution into an empty matchbox, soap can be obtained after drying.
6. Try this soap to wash your handkerchief.
In simple words: First, prepare your workspace, then gather water. Next, carefully mix sodium hydroxide and let it cool. After that, add coconut oil slowly while stirring. Finally, pour the mixture into a mold to dry and then test your homemade soap.

🎯 Exam Tip: When arranging steps for an experiment, always start with preparation and safety, then move to the actual mixing and reaction, and finally to the finishing and testing stages.

VI. Analogy:

Question 1. Urea : Inorganic fertilizer :: Vermi Compost: ...........
Answer: Natural Fertilizer
In simple words: Just like urea is a man-made fertilizer, vermicompost is a natural fertilizer. Vermicompost is made from organic waste using earthworms.

🎯 Exam Tip: Analogies test your understanding of classifications; identify if the items are natural, artificial, or a category. Here, it is about organic vs. inorganic fertilizers.

Question 2. ........... : Natural Adhesives :: Cello tape : Artificial Adhesives
Answer: Starch
In simple words: Starch is a natural glue, just as cello tape is a man-made glue. This shows the difference between glues from nature and glues made in factories.

🎯 Exam Tip: Focus on the source of the material – whether it's from nature or made artificially – to complete analogies correctly.

Question 3. ........... : Mortar : : Construction of bridges : Concrete
Answer: Construction of house walls.
In simple words: Mortar is used to build house walls, similar to how concrete is used to build bridges. Both are essential building materials for different structures.

🎯 Exam Tip: For construction analogies, identify the material and its primary application or structure it is used for.

VII. Give Very Short Answer:

Question 1. What are the principal nutrients?
Answer: Principal nutrients are NPK.
1. Nitrogen (N)
2. Phosphorus (P)
3. Potassium (K)
In simple words: The main nutrients plants need are Nitrogen, Phosphorus, and Potassium, often called NPK. These help plants grow strong and healthy.

🎯 Exam Tip: Listing the full names of the elements along with their chemical symbols ensures complete accuracy.

Question 2. What are fertilizers?
Answer: Fertilizers are organic (or) inorganic materials that we add to the soil to provide one (or) more nutrients to the soil.
In simple words: Fertilizers are special substances, either natural or man-made, that we put in soil to give plants extra food. They help plants get all the nutrients they need to grow well.

🎯 Exam Tip: A good definition of fertilizers should include their purpose (providing nutrients) and their types (organic/inorganic).

Question 3. Give two examples of organic fertilizers?
Answer:
1. Compost
2. Vermicompost
In simple words: Two examples of natural plant food are compost and vermicompost. Both are made from decayed organic matter and are good for the soil.

🎯 Exam Tip: When asked for examples, provide distinct and clear options that fit the category.

Question 4. Why is called inorganic fertilizers?
Answer: Inorganic fertilizers are made in labs. They use natural elements and put them through chemical changes. These processes help to create stronger plant food.
In simple words: Fertilizers made in factories from natural things using chemical reactions are called inorganic fertilizers.

🎯 Exam Tip: Remember that inorganic fertilizers are human-made in a controlled environment to provide specific nutrients to plants.

Question 5. Why is called Portland cement?
Answer: Portland cement got its name because it looked like the strong building stones found in Portland, England. This name helped people understand its quality.
In simple words: It was named "Portland" cement because it looked like the good quality building stones from Portland, England.

🎯 Exam Tip: Focus on the visual resemblance to the Portland stone as the key reason for its naming.

VII. Answer In Details

Question 1. What is Epsum? Mention its uses.
Answer:
1. Epsom salt is chemically called magnesium sulfate hydrate.
2. Its molecular formula is \( \text{MgSO}_4 \cdot 7\text{H}_2\text{O} \). This hydrate form means it contains water molecules within its crystal structure.
Uses:
1. It helps to ease stress and relax the body.
2. It makes muscles and nerves work correctly.
3. It is used as a medicine for certain skin problems.
4. It helps in making plants grow better in farming.
In simple words: Epsom salt is magnesium sulfate hydrate, and it is used for relaxing the body, helping muscles, treating skin, and improving plant growth.

🎯 Exam Tip: When asked for definition and uses, always list the chemical name and formula for full marks, then clearly enumerate each use.

Question 2. Write about the Phenol and its uses.
Answer:
Phenol:
1. Phenol is an organic compound called carbolic acid.
2. Its chemical formula is \( \text{C}_6\text{H}_5\text{OH} \). This structure shows it is an aromatic alcohol.
3. It is a weak acid.
4. It is a white crystalline powder that can easily become a gas.
5. It starts as a clear liquid but turns red when it touches dust.
6. It can irritate human skin if touched.
Uses:
1. It is used in industries.
2. A small amount of phenol is used in mouthwash and as a cleaner for homes.
3. It acts as a surgical antiseptic, killing tiny harmful germs.
In simple words: Phenol is carbolic acid, a white crystalline powder with formula \( \text{C}_6\text{H}_5\text{OH} \), used in industries, mouthwash, and as an antiseptic.

🎯 Exam Tip: For compounds like phenol, remember to include its common name (carbolic acid) and molecular formula, along with a few key properties and uses.

Question 3. Tabulate the nutrients present in inorganic fertilizers.
Answer: The table below shows the common inorganic fertilizers and the percentage of essential nutrients they provide, which are vital for plant health.

🎯 Exam Tip: When asked to tabulate, create a clear table with proper headings and ensure all percentages are accurately listed for each fertilizer.