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ScienceClass 6CBSE

Differentiate among opaque, translucent and transparent materials, giving one example of each.

Those substances through which objects cannot be seen are termed as opaque substances. Example: wood, stone. Those substances through which objects can be seen but not clearly are termed as translucent substances. Example: frosted glass, oiled paper. Those substances through which objects can be seen clearly are termed as transparent substances. Example: crystal clear water, glass.

ScienceClass 6CBSE

Why do you think oxygen dissolved in water is important for the survival of aquatic animals and plants?

Aquatic animals and plants use oxygen which is dissolved in water for breathing and photosynthesis.

ScienceClass 6CBSE

Chalk, iron nail, wood, aluminium, candle, cotton usually look different from each other. Give some properties by which we can prove that these materials are different.

Solution: Few properties by which we can prove that these materials are different: Chalk – Hard, rough, non-lustrous Iron nail – Hard, smooth, lustrous Wood – Hard, rough, non-lustrous Aluminium – Hard, smooth, lustrous Candle – Hard, smooth, non-lustrous Cotton – Soft, smooth, non-lustrous

ScienceClass 6CBSE

Pick five objects from the word box given as Fig. 4.1 which are opaque and would sink in water. O S T P L E A T L E E R C O I N A A O N K C F S A E E I W E L L Y L R R

Solution: Objects that are opaque and would sink in water are: Coin Stone Key Pencil Eraser

ScienceClass 6CBSE

Match the objects given in column I with the materials given in column II. Column I Column II (a) Surgical instruments (i) Plastic (b) Newspaper (ii) Animal product (c) Electrical switches (iii) Steel (d) Wool (iv) Plant product

The correct match is: Column I Column II (a) Surgical instruments (iii) Steel (b) Newspaper (iv) Plant product (c) Electrical switches (i) Plastic (d) Wool (ii) Animal product

ScienceClass 6CBSE

Arrange the jumbled words to arrive at the appropriate names of materials and also write two uses of each. (a) milaunuim (b) tcaslpi (c) soekrnee gavnier

The arranged word are: Aluminium – It can be used to wrap food in the foil, in making aircraft, Plastic – It can be used as buckets/pencil box, Kerosene – It can be used as fuel, solvent, Vinegar – It can be used as preservative, food ingredients,

ScienceClass 6CBSE

During 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. Name of the material Appearance (Hard/Soft) Transparency (Transparent/Translucent/Opaque) Floats/Sinks in water Soluble/Insoluble in water

Solution: Name of the material Appearance (Hard/Soft) Transparency (Transparent/Translucent/Opaque) Floats/Sinks in water Soluble/Insoluble in water Lump of salt Hard Opaque Sinks Soluble Green grass Soft Opaque Floats Insoluble Broken glass piece Hard Transparent Sinks Insoluble Thermocol box Soft Opaque Floats Insoluble Pen Hard Opaque Floats Insoluble Iron nail Hard Opaque Sinks Insoluble Glass marbles Hard Transparent Sinks Insoluble Hair Hard Opaque Floats Insoluble Naphthalene ball Hard Opaque Floats Insoluble A piece of sugar candy Hard Opaque Sinks Soluble

ScienceClass 6CBSE

You are provided with the following materials – turmeric, honey, mustard oil, water, glucose, rice flour, groundnut oil. Make any three pairs of substances where one substance is soluble in the other and any three pairs of substances where one substance remains insoluble in the other substances.

Solution: Soluble pairs Honey – water Mustard oil – groundnut oil Glucose – water Insoluble pairs Mustard oil – water Turmeric – water Rice flour – water

ScienceClass 6CBSE

Which among the following materials would you identify as soft materials and why? Ice, rubber band, leaf, eraser, pencil, pearl, a piece of wooden board, cooked rice, pulses and fresh chapati.

Solution: Leaf, rubber band, cooked rice, eraser and fresh chapati are soft materials because they can be scratched or compressed easily.

ScienceClass 6CBSE

Take a small cotton ball and place it in a tumbler/ bowl filled with water. Observe it for atleast 10 minutes. Will it float or sink in water and why?

Solution: Initially the cotton ball floats on water since it is lighter. Slowly it absorbs water and becomes heavy and later sinks in water.

ScienceClass 6CBSE

On a bright sunny day, Shikha was playing hide and seek with her brother. She hid herself behind a glass door. Do you think her brother will be able to locate her? If yes, why? If no, why not?

Yes, Shikha’s brother could locate her since the glass door which she hid is transparent in nature.

ScienceClass 6CBSE

Mixtures of red chilli powder in water, butter in water, petrol in water, and honey in water were given to Radha, Sudha, Sofia and Raveena, respectively. Whose mixture is in solution form?

Raveena will get the mixture in solution form. Since, honey and water are soluble with each other hence a solution will be formed when honey is mixed with water.

ScienceClass 6CBSE

lt was Paheli’s birthday. Her grandmother gave her two gifts made of metals, one old dull silver spoon and a pair of lustrous gold earrings. She was surprised to see the difference in the appearance of the two metals. Can you explain the reason for this difference?

Paheli could see the difference in the appearance of two metals since, silver reacts with some gases like hydrogen sulphide and loses its shine in moist air. Gold is a noble metal which does not react with the gases present in the atmosphere.

ScienceClass 6CBSE

Which type of the following materials is used for making the front glass (wind screen) of a car? (a) Transparent (b) Translucent (c) Opaque All the above

Solution: : Transparent Transparent glass is used for making the front glass of a car so that everything can be seen clearly.

ScienceClass 6CBSE

Find the odd one out from the following. (a) Tawa (b) Spade (c) Pressure cooker Eraser

Solution: (d): Eraser Eraser is made up of rubber while tawa, pressure cooker and spade are made up of metal.

ScienceClass 6CBSE

Which of the following statements is not true? (a) Materials are grouped for convenience. (b) Materials are grouped to study their properties. (c) Materials are grouped for fun. Materials are grouped according to their uses.

Solution: (c): Materials are grouped for fun. Materials are usually grouped to study their properties and according to their uses in systematic manner. Hence materials are not grouped for fun.

ScienceClass 6CBSE

Which of the following materials is not lustrous? (a) Gold (b) Silver (c) Wood Diamond

Solution: (c): Wood Wood is not lustrous since it is not a crystalline substance.

ScienceClass 6CBSE

Which among the following are commonly used for making a safety pin? (a) Wood and glass (b) Plastic and glass (c) Leather and plastic Steel and plastic

Solution: (d): Steel and plastic Steel can be moulded to get sharp points and plastic is used to seal the edges. Hence steel and plastic are used for making safety pins.

ScienceClass 6CBSE

Which pair of substances among the following would float in a tumbler half filled with water? (a) Cotton thread, thermocol (b) Feather, plastic ball (c) Pin, oil drops Rubber band, coin

Solution: (b): Feather, plastic ball Feather and plastic ball will float on water since they are lighter than water.

ScienceClass 6CBSE

While doing an activity in class, the teacher asked Paheli to handover a translucent material. Which among the following materials will Paheli pick and give her teacher? (a) Glass tumbler (b) Mirror (c) Muslin cloth Aluminium foil

Solution: (c): Muslin cloth Muslin cloth is translucent since we can see through it but not clearly. Glass tumbler is transparent. Mirror and aluminum foil are opaque.

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