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Practice each question, then open the answer or worked solution.
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.
Ans: Eraser, rubber band, cooked rice, fresh chapati and leaf are soft materials because they can be easily compressed and scratched easily.
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.
Ans: (a) Soluble pairs:
(i) Glucose – water
(ii) Mustard oil – groundnut oil
(iii) Honey – water
(b) Insoluble pairs:
(i) Rice flour – water
(ii) Turmeric – water
(iii) Mustard oil – water
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.
Material | Hard/Soft | Transparency | Floats/sinks in water | Soluble/insoluble in water |
Ans:
Material | Hard/Soft | Transparency | Floats/sinks in water | Soluble/insoluble in water |
Lump of salt | Hard | Opaque | Floats | Soluble |
Green grass | Soft | Opaque | Sinks | Insoluble |
Broken glass piece | Hard | Opaque | Sinks | Insoluble |
Thermocol box | Soft | Opaque | Sinks | Insoluble |
Pen | Hard | Opaque | Floats | Insoluble |
Iron nail | Hard | Opaque | Sinks | Insoluble |
Glass | Hard | Transparent | Sinks | Insoluble |
Marble | Hard | Opaque | Sinks | Insoluble |
Hair | Hard | Opaque | Sinks | Insoluble |
Naphthalene ball | Hard | Opaque | Sinks | Insoluble |
A piece of sugar candy | Hard | Opaque | Sinks | Soluble |
Arrange the jumbled words to arrive at the appropriate names of materials and also write two uses of each.
(a) milaunuim
(b) tcaslpi
(c) serene
(d) gavnier
Ans: Aluminium
Uses: It is used in aeroplane equipment and as foils.
Ans: Plastic
Uses: Many objects are made, like bucket, lunch box, and pencil box.
Ans: Kerosene
Uses: It's used as a solvent and a fire starter.
Ans: Vinegar
Uses: Food ingredients, preservatives.
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 |
Ans: The correct match is-
Column I | Column II | ||
(a) | Surgical instruments | (iii) | Steel(Rust-free) |
(b) | Newspaper | (iv) | Plant Product(Paper) |
(c) | Electrical switches | (i) | Plastic(Bad conductor of electricity) |
(d) | Wool | (ii) | Animal Product(Obtained from sheep) |
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 |
Ans: Five objects in the puzzle that are opaque and would sink in water are:
i. Coin
ii. Pen
iii. Stone
iv. Eraser
v. Coal