Sorting Materials and Groups

Explanation:

The correct option is (c) Soft drink

Soft drinks contain acids and sugars that can react with the iron in the nail and create an environment that is conducive to rusting. The acid in the soft drink corrodes the protective oxide layer on the iron, and the sugar attracts moisture and holds it against the surface of the nail, increasing the likelihood of rusting.

Rusting leads to the loss of shine resulting in dull appearance.

Explanation:

The correct option is (c) Glucose.

Chalk powder (a) is insoluble in water and will not dissolve in it. Tea leaves (b) are partially soluble in water, but not completely, and will leave some residue behind. Sawdust (d) is insoluble in water and will not dissolve in it. Glucose (c), on the other hand, is a simple sugar that is completely soluble in water, and will dissolve completely when mixed with it.

Explanation:

The correct option is (c) (i) and (iv)

A magnifying glass (i) is a convex lens that can be used to magnify small objects and is itself transparent. A mirror (ii) is not transparent, as it reflects light and does not allow it to pass through. A stainless steel plate (iii) is not transparent either, as it is an opaque material that does not allow light to pass through. A glass tumbler (iv) is a transparent material that allows light to pass through it, making it possible to see through the glass.

Explanation:

The correct option is (a) (i) and (iii)

A magnet (i) is opaque as it is made of metal, which does not allow light to pass through it. Glass spectacles (ii) are transparent that allow light to pass through. A mirror (iii) is opaque as it reflects light and does not allow it to pass through. Paper stained with oil (iv) is translucent, allowing some light to pass through it, but it is not opaque.

Explanation:

The correct option is (b) Muslin cloth

Aluminium foil (a) is an opaque material that does not allow any light to pass through it. Muslin cloth (b) is a translucent material, which allows some light to pass through it but diffuses the light and scatters it in different directions. Mirror (c) is an opaque material that reflects light and does not allow it to pass through. Glass tumbler (d) is a transparent material that allows light to pass through it without scattering it in different directions.

Explanation:

The correct answer is (a) Feather, plastic ball.

Feather (a) and plastic ball (a) both have a lower density than water and, therefore, will float when placed in a tumbler half-filled with water. 

Cotton thread (b) will absorb water and therefore sink while thermocol (b) will float as it is less dense than water. 

Rubber band (c) and coin (c) have a higher density than water and, therefore, will sink when placed in a tumbler half-filled with water.

Similarly, pin (d) has a higher density than water and will sink, while oil drops (d) will float on top of the water as they have a lower density than water.

Explanation:

The correct option is (b) Steel and plastic.

A safety pin consists of two metal arms that are joined together at one end by a spring mechanism. The arms are made of steel, which is strong and durable. The spring mechanism is also made of steel. The plastic part of a safety pin is the cap that covers the sharp end of the pin to prevent injury. The plastic cap also makes it easier to handle the pin.

Explanation:

The correct option is (d) Wood.

Silver (a), gold (b), and diamond (c) are all lustrous materials, which means that they reflect light and have a shiny appearance. Wood (d) is not lustrous as it does not reflect light and has a dull appearance.

Explanation:

Which of the following statements is not true?

(a) Materials are grouped for fun.

(b) Materials are grouped according to their uses.

(c) Materials are grouped for convenience.

(d) Materials are grouped to study their properties.

Find the odd one out from the following.

(a) Spade

(b) Tawa

(c) Eraser

(d) Pressure cooker

Explanation:

The correct option is (c) Eraser.

A spade (a) is usually made of metal, such as steel, and is used for digging. A tawa (b) is a flat round griddle used in Indian cooking, and is made of metal, such as cast iron, steel or aluminum. A pressure cooker (d) is a cooking appliance used to cook food quickly under high pressure, and is usually made of metal, such as aluminum or stainless steel.

However, an eraser (c) is not made of metal, but of rubber or a similar material. It is used to remove pencil marks from paper by rubbing them off.

Explanation:

The correct answer is (b) Transparent.

The front glass or windscreen of a car needs to be transparent so that the driver can see clearly through it while driving. A transparent material allows light to pass through it without scattering, resulting in a clear view. Materials such as tempered glass or laminated glass are commonly used for making the front glass of a car, both of which are transparent materials.

Opaque materials (a) do not allow light to pass through them at all, while translucent materials (c) allow some light to pass through but also scatter it, resulting in a blurry or hazy appearance. These types of materials would not be suitable for making the front glass of a car.

Explanation:

The difference in the appearance of the two metals, the old dull silver spoon and the lustrous gold earrings, is due to their properties and characteristics.

Silver, like many other metals, is prone to oxidation and tarnishing over time. When exposed to air and moisture, silver can react with sulfur-containing compounds in the environment and form a layer of silver sulfide on its surface, which appears as a dull and dark coating. This is why the old silver spoon appears dull.

Gold, on the other hand, is a noble metal and is relatively inert and resistant to oxidation and tarnishing. It does not react with air or moisture in the environment, which is why the gold earrings appear lustrous and shiny.

Explanation:

A solution is a homogeneous mixture of two or more substances.

Out of the given mixtures, the mixture of honey in water is in solution form. Honey dissolves easily in water to form a homogeneous mixture because it is a polar substance, and water is also a polar solvent. When honey is added to water, its components dissolve and become evenly distributed throughout the water, forming a solution.

In contrast, red chilli powder, butter, and petrol are not soluble in water and do not form solutions.

Therefore, Raveena's mixture of honey in water is in solution form.

Explanation:

Shikha's brother will be able to locate her even if she is hiding behind a glass door because glass is a transparent material, which means it allows the light to pass through it. When Shikha stands behind the glass door she is still visible to her brother.

Explanation:

When a small cotton ball is placed in a tumbler or bowl filled with water, it will initially float on the surface of the water until it absorbs water and gets heavier then the cotton ball will sink.

Because as it slowly absorbs water it gets denser and starts sinking.

Explanation:

Soft materials are those that can be easily deformed or compressed by an external force.

Based on this definition, the soft materials from the given list are:

1. Rubber band: It can be easily stretched and deformed by an external force.

2. Leaf: It is a soft material that can be easily scratched or damaged by other materials.

3. Cooked rice: These are soft materials that can be easily compressed by external force.

4. Eraser: It is a soft material and can be deformed by external force.

5. Fresh chapati: It is a soft material that can be easily torn apart or compressed by an external force.

The other materials from the list are not considered as soft materials.

Explanation:

Pairs of substances where one substance is soluble in the other:

Turmeric and water - Turmeric is soluble in water.

Glucose and water - Glucose is soluble in water.

Rice flour and water - Rice flour is soluble in water.

Pairs of substances where one substance remains insoluble in the other:

Honey and groundnut oil - Honey is insoluble in groundnut oil.

Mustard oil and water - Mustard oil is insoluble in water.

Turmeric and groundnut oil - Turmeric is insoluble in groundnut oil.

Explanation:

During the summer holidays, a group of children collected a lump of salt, green grass, broken glass piece, a small thermocol box, pen, iron nail, glass marbles, hair, naphthalene ball, a piece of sugar candy (mishri) and tried to group them on the basis of properties given in table 4.1 below. Help them in filling the table.

Answer:

Explanation:

The unjumbled words and their uses:

(a) Aluminium

1. Used in the manufacturing of aircraft due to its lightweight and high strength.

2. Used in the production of foil packaging for food and beverage products.

(b) Plastic

1. Used in the production of various consumer products such as bottles, bags, toys, and electronics.

2. Used in the automotive industry for making car parts, dashboard, and bumpers.

(c) Kerosene

1. Used as a fuel for heating, cooking, and lighting.

2. Used as a solvent in paint and varnish industry.

(d) Vinegar

1. Used as a food preservative and condiment.

2. Used in cleaning and disinfecting household surfaces.

Explanation:

Objects that would sink in water and also are opaque from the box are:

1. Pencil

2. Coin

3. Eraser

4. Stone

5. Key

Explanation:

Chalk, iron nail, wood, aluminium, candle, and cotton have different physical and chemical properties that help us differentiate them. Some of the properties that can be used to prove their differences are:

1. Hardness: Chalk is soft, iron nail is hard, wood is hard but can be easily cut, aluminium is relatively soft, candle wax is soft, and cotton is soft and fluffy.

2. Density: Chalk and wood are less dense than water and float, iron nail and aluminium are denser than water and sink, candle wax and cotton are less dense than water and float.

3. Conductivity: Iron nail is a good conductor of electricity and heat, aluminium is a good conductor of electricity but not heat and wood, chalk, candle wax and cotton are non-conductors.

4. Appearance: Chalk is a white, powdery substance, iron nail is metallic and silver, wood is brown and fibrous, aluminium is metallic and light gray, candle wax is a waxy substance, and cotton is white and fluffy.

5. Combustibility: Chalk, aluminium, and cotton do not burn easily, iron nail does not burn but can rust, and wood and candle wax burns easily.

These properties can be used to prove that these materials are different from each other.

Explanation:

Oxygen is necessary for the survival of all living organisms as it is involved in the process of respiration, which releases energy from food. Aquatic animals and plants living in water also require oxygen for respiration. However, unlike in air, the amount of dissolved oxygen in water is low. Therefore, it is crucial for the survival of aquatic organisms that there is enough oxygen dissolved in water for them to breathe.

Aquatic animals such as fish extract oxygen from the water through their gills, while aquatic plants release oxygen into the water during photosynthesis. Oxygen also helps in the decomposition of organic matter, which is important for maintaining the ecological balance in aquatic ecosystems.

In summary, the presence of oxygen dissolved in water is essential for the survival of aquatic animals and plants because it is involved in respiration, provides energy, and helps in maintaining the ecological balance in aquatic ecosystems.

Explanation:

Opaque, translucent, and transparent are three categories used to describe how light interacts with materials.

Opaque materials do not allow light to pass through them, making it impossible to see through them. When light falls on an opaque object, it either bounces back or gets absorbed. Examples of opaque materials are metals, wood, and rocks.

Translucent materials allow some light to pass through them but not enough to clearly see through them. When light falls on a translucent object, it scatters in different directions, making objects behind the material appear blurry or distorted. Examples of translucent materials are wax paper, frosted glass, and tissue paper.

Transparent materials allow light to pass through them, making it easy to see through them. When light falls on a transparent object, it travels through the material without scattering, allowing objects behind the material to appear clearly. Examples of transparent materials are glass, water, and air.

In summary, opaque materials do not allow light to pass through them, translucent materials allow some light to pass through but not enough to see through them clearly, and transparent materials allow light to pass through, making it easy to see through them.

Explanation:

Solubility is a measure of how much of a substance (called the solute) can dissolve in a given amount of solvent (usually water) at a particular temperature and pressure. Some substances dissolve easily in water, while others do not dissolve at all.

Based on the given substances, the following can be identified as soluble or insoluble in water:

Soluble in water:

• Glucose

• Sugar

• Honey (partially soluble)

• Salt

• Copper sulphate crystals

Insoluble in water:

• Sawdust

• Sand

• Mustard oil

• Wheat flour

• Soil

• Petals of a flower

• Chalk powder

Sugar, salt, glucose, and copper sulphate crystals are soluble in water because they dissolve completely in water to form a clear solution. Honey is partially soluble in water, which means that they dissolve to some extent but not completely.

On the other hand, sand, sawdust, chalk powder, mustard oil, petals of a flower, soil, and wheat flour are insoluble in water. They do not dissolve in water and can be seen as separate particles in water.

Solubility in water is an important property of substances as it affects their use and handling. For example, sugar and salt are commonly used in cooking and are added to water to dissolve and form a solution. Copper sulphate crystals are used in agriculture as a fungicide and are dissolved in water to be sprayed on crops. On the other hand, sawdust and soil are used as construction materials and their insolubility in water makes them suitable for these applications.