Nutrition and Diet

Question 1:

Fill in the blanks.
(a) The process of intake of food and utilising it for all life processes is called .......... .
(b) All the substances in our food which are useful for various bodily processes are called .......... .
(c) Carbohydrates and .......... provide .......... to our body.
(d) In a balanced diet, all the nutrients are present in the ....... proportion.
(e) In the food pyramid, cereals are given the maximum space because they fulfil our .......... requirement.
(f) Intake of more food than necessary causes .......... .

ANSWER:

(a) The process of intake of food and utilising it for all life processes is called nutrition.
(b) All the substances in our food which are useful for various bodily processes are called nutrients.
(c) Carbohydrates and fats provide energy to our body.
(d) In a balanced diet, all the nutrients are present in the right proportion.
(e) In the food pyramid, cereals are given the maximum space because they fulfil our nutritional requirement.
(f) Intake of more food than necessary causes overnutrition.

Page No 56:

Question 2:

Spot the following in the table of vitamins and minerals.
(a) The nutrient present in citrous fruits.
(b) Vitamins / minerals present in milk.
(c) Causes and symptoms of night blindness, scurvy, rickets, beriberi.
(d) Foods required to prevent the above diseases.
(e) Causes of anaemia.
(f) Essential mineral for healthy bones and teeth.
(g) Sensory organ affected due to the deficiency of Vitamin A

ANSWER:

(a) The nutrient present in citrous fruits- Vitamin C
(b) Vitamins / minerals present in milk- Vitamin B₁₂ and Vitamin D.
(c) Causes and symptoms of night blindness, scurvy, rickets, beriberi
 

Disease	Causes	Symptoms
Night blindness	Deficiency of Vitamin A	Inability to see in dim light
Scurvy	Deficiency of Vitamin C	Bleeding of gums
Rickets	Deficiency of Vitamin D	Softening of pones causing pain and fractures
Beri beri	Deficiency of Vitamin B1	Nerve disorders

(d) Foods required to prevent the above diseases.
 

Disease	Foods to avoid these diseases
Night blindness	Carrot, milk, butter, dark green vegetables, sweet potato
Scurvy	Amla, kiwi, oranges, other citrus fruits, tomato, green leafy vegetables
Rickets	Milk, fish, eggs and butter
Beri beri	Milk, fish, meat, cereals, nuts, pulses

(e) Causes of anaemia- defeciency of iron can result in anaemia as it is required for the formation of red blood cells.
(f) Essential mineral for healthy bones and teeth- Vitamin D
(g) Sensory organ affected due to the deficiency of Vitamin A- Eyes

Page No 56:

Question 3:

Choose the correct alternative.

(a) Pulses are a very good source of .......... .

(1) carbohydrates	(2) proteins
(3) fats	(4) minerals

(b) .......... provide maximum energy to the body.

(1) Cereals	(2) Leafy vegetables
(3) Water	(4) Amla

(c) Goitre is caused by a deficiency of the mineral .......... .

(1) iron	(2) calcium
(3) iodine	(4) potassium

(d) .......... is a type of junk food.

(1) Orange	(2) Milk
(3) Bhakri	(4) Chocolate

ANSWER:

(a) Pulses are a very good source of proteins.
(b)Cereals provide maximum energy to the body.
(c) Goitre is caused by a deficiency of the mineral iodine.
(d) Chocolate is a type of junk food.

Page No 56:

Question 4:

Use the food pyramid to select food items of your choice for three days.
Conditions :
(1) The diet for all three days should be balanced.
(2) There should be variety in the items chosen for the three days.

ANSWER:

Day 1-
Cereal like cornflakes and milk, apple, roti, sabzi and dal

Day 2
Bread and butter with milk, rice/ roti and chicken, curd, any one type of fruit, salad

Day 3
Poha, green vegetable and dal with rice or roti, raita, one fruit, vegetable sandwich.

Substances in Daily Use

Substances in Daily Use

Question 1:

Fill in the blanks using proper words.
(a) Rubber made by vulcanization is a ...... material.
(b) Man-made materials are made by .......... natural materials.
(c) ............. thread was developed simultaneously in New York and London.
(d) Rayon is also known as ............

ANSWER:

(a) Rubber made by vulcanization is a man-made material.
(b) Man-made materials are made by processing natural materials.
(c) Nylon thread was developed simultaneously in New York and London.
(d) Rayon is also known as synthetic silk.

Question 2:

Answer the following questions.

ANSWER:

(a) Why did the need for man-made materials arise?

a. For several years, humans have been dependant on natural materials to meet their demands. However, there has been a shift towards the use of man made materials as well. Increasing population, deforestation and limited natural resources are some of the reasons due to which the need for man made materials arised. Another reason which led to the increase in the use of man made material was to get a comfortable lifestyle.

(b) Which are the natural materials obtained from plants and animals?

b. 

Sources	Natural material	Objects
Plants	Wood	Furniture
	Rubber	Ballon, tyres etc.
	Cotton	Clothes
Animals	Fur	Hats, Sweaters
	Leather	Handbags, shoes
	Silk	Sarees

(c) What is vulcanization?
c. Vulcanization is the process carried out for the production of rubber. In this process, raw rubber is heated with a mixture of sulphur and an appropriate additive, at a temperature range of 61.85${\mathrm{<merror><mtext>Unknown\; node\; type:\; sup</mtext></merror>}}^{}$ C to 141.85⁰C for three to four hours. Sulphur is added to give toughness to rubber.

(d) Which natural materials are used to obtain fibres?

d. Natural materials obtained from plants and animals are used to obtain fibers. For example, wool and silk are natural materials of animal origin which are used for obtaining fibers. Wool is obtained from the fleece (hair) of sheep or yak and silk is obtained from the cocoons of a silk moth. Cotton and jute are examples of natural materials of plant origin which are used for obtaining fibers.

Question 3:

What are we used for ?
(a) Soil
(b) Wood
(c) Nylon
(d) Paper
(e) Rubber

ANSWER:

a. Soil- It is used in construction, pottery, medicine and cosmetics.
b. Wood- It is used in making furnitures, as a source of fuel, utensils, hand tools, musical instruments, wooden toys etc.
c. Nylon- It is used in making canopies of parachutes, tents, sleeping bags, sails, rope, tennis strings, fishing poles and lines, cookware etc.
d. Paper- It is used in making bags, envelopes, notebooks, packaging purpose etc.
e. Rubber- Balloons, erasers, rubber toys, rubber balls etc.

Question 4:

How is paper manufactured? Write in your own words.

ANSWER:

Paper is manufactured by the following process:

• Logs of wood are made to pass through a debarker, where the barks of the tree are separated.
• Then the wood is chopped into small pieces and is mixed with some chemicals and water in digetser for the formation of the pulp.
• The obtained pulp is washed refined and sometimes even bleached.
• The pulp is made to travel down the screen to remove excess of water and then to the rollers where it is being dried and squeezed between large rollers to form rolls of paper. 

Question 5:

Give scientific reasons.

ANSWER:

(a) We must use cotton clothes in summer.

a. We must use cotton clothes in summers because they protect us from the heat of the sun. They absorb sweat and help keep our bodies cool. The pores in cotton clothes allow the free movement of air, which helps cool our bodies.

(b) We must observe economy in the use of materials.
b. We must observe economy in the use of materials because they directly or indirectly affect our environment. Most of the natural materials which we obtain from our environment are exhaustible/non renewable resources i.e. once these resources are finished they cannot be renewed again or even if they can, it would take several years to do so. For example, our forests from where we obtain wood are precious resources because once a forest is destroyed, it would take several years to renew that forest. Also, destroying the forests for our needs affects the habitat of several other species of organisms and plants. The man made materials which we use are largely non biodegradable for example plastic etc. Increased use of man made materials pose a threat to the environment because their disposal is not easy and leads to environmental pollution. These examples state the importance of judicious use of both natural and man made materials.

(c) Saving paper is the need of the hour.

c. We very well know that paper is obtained from trees. Trees are important resources because they not only provide us with wood or paper but are also a habitat for various organisms. They are important in maintaining the climate as well. The more paper we use or waste, the more no. of trees will have to be cut down for this purpose, thus leading to v arious kinds of harmful effects on our environment. We should make a genuine effort in saving paper by adopting small steps which can make a huge difference.

(d) Man-made materials have more demand.

d. Man made materials have more demand because of their characteristics like easy to use, low cost of production, cheaper products and variety of things which can be made from them.

(e) Humus is a natural material.

e. Humus is a natural material because its formation is a natural process. It is the dark-coloured layer of top soil that is rich in nutrients. The decomposers convert the dead plants and animals into humus that is utilised by the plants. It increases the fertility of the soil.

Question 6:

Find out.
(1) How is lac obtained from nature?

ANSWER:

a. Lac is a natural resin and is a product of animal origin. It is secreted by an insect, known as lac-insect. In order to obtain lac, these insects are cultured and the technique is called lac-culture. Lac culture requires proper care of host plants, regular pruning of host plants, propagation, collection and processing of lac. The lac insect lives as a parasite, feeding on the sap of certain trees and shrubs. Lac secretion begins as soon as the larva of the insect settles on the plant. Intially, lac has a shining appearance but later on it turns harder on coming in contact wih air.
This lac is then collected and used for making jewellery etc.


(2) How are pearls obtained?
b. Pearls are precious jewels and the only gems created by a living animal. They are formed when a microscopic foreign object finds its way inside a mussel or oyster.

The animal coats the object with a substance called nacre. With time, several layers of nacre build up over the foreign material thus leading to the formation of a pearl. These oyesters/mussels are collectd from the sea and opened to collect these pearls. 

HCF and LCM

Page No 15:

Question 1:

Which number is neither a prime number nor a composite number?

ANSWER:

1 is neither a prime number nor a composite number.

Page No 15:

Question 2:

Which of the following are pairs of co-primes?
(i) 8, 14
(ii) 4, 5
(iii) 17, 19
(iv) 27, 15
 

ANSWER:

Two numbers which have only 1 as a common factor are said to be co-prime or relatively prime or mutually prime numbers.
We can write 17 as 17 × 1 and 19 as 17 × 1.
Hence, 17 and 19 is a pair of co-prime numbers.

Page No 15:

Question 3:

List the prime numbers from 25 to 100 and say how many they are.

ANSWER:

There are a total of 16 prime numbers between 25 and 100 which are 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

Page No 15:

Question 4:

Write all the twin prime numbers from 51 to 100.

ANSWER:

If the difference between two co-prime numbers is 2, the numbers are said to be twin prime numbers.
Hence, the twin prime numbers between 51 and 100 are 59 and 61, 71 and 73.

Page No 15:

Question 5:

Write 5 pairs of twin prime numbers from 1 to 50.

ANSWER:

If the difference between two co-prime numbers is 2 then, the numbers are said to be twin prime numbers.
Hence, the twin prime numbers from 1 to 50 are (2,3), (5,7), (11,12), (17,19) and (29,30).

Page No 15:

Question 6:

Which are the even prime numbers?

ANSWER:

There is only even prime number which is 2.

Page No 17:

Question 1:

Factorise the following numbers into primes.
(i)    32
(ii)   57
(iii)  23
(iv)  150
(v)   216
(vi)  208
(vii) 765
(viii) 342
(ix)   377
(x)    559

ANSWER:

(i)
32 = 2 × 16
= 2 × 2 × 8
= 2 × 2 × 2 × 4
​= 2 × 2 × 2 × 2 × 2
(ii)
57 = 3 × 19
(iii)
23 = 23 × 1
(iv)
150 = 2 × 75
= 2 × 3 × 25
​= 2 × 3 × 5 × 5
(v)
216 =  2 × 108
 =  2 × 2 × 54
 =  2 × 2 × 2 × 27
 =  2 × 2 × 2 × 3 × 9
 =  2 × 2 × 2 × 3 × 3 × 3
(vi)
208 = 2 × 104
= 2 × 2 × 52
= 2 × 2 × 2 × 26
= 2 × 2 × 2 × 2 × 13
(vii)
765 = 3 × 255
= 3 × 3 × 85
= 3 × 3 × 5 × 17
(viii)
342 = 2 × 171
= 2 × 3 × 57
= 2 × 3 × 3 × 19
(ix)
377 = 13 × 29
(x)
559 = 13 × 43

Page No 19:

Question 1:

Find the HCF.
(i)     25, 40
(ii)    56, 32
(iii)   40, 60, 75
(iv)   16, 27
(v)    18, 32, 48
(vi)   105, 154
(vii)  42, 45, 48
(viii) 57, 75, 102
(ix)   56, 57
(x)    777, 315, 588

ANSWER:

(i)
 
HCF = 5

(ii)
 
HCF = 2 × 2 × 2= 8

(iii)

HCF = 5

(iv)
 
HCF = 1

(v)
 
HCF = 2

(vi)
 
HCF = 7

(vii)
 
HCF = 3

(viii)
 
HCF = 3

(ix)
 
HCF = 1

(x)
 
HCF = 3 × 7 = 21

Page No 19:

Question 2:

Find the HCF by the division method and reduce to the simplest form.

(i) 275525$\frac{275}{525}$

(ii) 76133$\frac{76}{133}$

(iii) 16169$\frac{161}{69}$

ANSWER:

(i) 

HCF = 25
 ∴275/525=275÷25 / 525÷25=11/21
(ii)

HCF = 19
 ∴76/133=76÷19/133÷19=4/7
(iii) 

HCF = 23
∴161/69=161÷23/69÷23=7/3

Page No 21:

Question 1:

Find the LCF.
(i)     12, 15
(ii)    6, 8, 10
(iii)   18, 32
(iv)   10, 15, 20
(v)    45, 86
(vi)   15, 30, 90
(vii)  105, 195
(viii) 12, 15, 45
(ix)   63, 81
(x)    18, 36, 27

ANSWER:

(i)

LCM = 3 × 5 × 4 = 60

(ii)

LCM = 2 × 3 × 4 × 5​ = 120

(iii)

LCM = 2 × 9 × 16 ​= 288

(iv)

LCM = 2 × 2 × 3 × 5 = 60

(v)

LCM = 45 × 86 = 3870

(vi)

LCM = 2 × 3 × 3 × 5 = 90

(vii)

LCM = 3 × 5 × 7 × 13 = 1365

(viii)

LCM = 2 × 2 × 3 × 3 × 5 = 180

(ix)

LCM = 3 × 3 × 3 × 3 × 5 = 567

(x)

​LCM = 2 × 2 × 3 × 3 × 3 = 108

Page No 21:

Question 2:

Find the HCF and LCM of the numbers given below. Verify that their product is equal to the product of the given numbers.
(i) 32, 37
(ii) 46, 51
(iii) 15, 60
(iv) 18, 63
(v) 78, 104

ANSWER:

(i) 

HCF = 1
LCM = 32 × 37 = 1184
Product of two numbers = 32 × 37 = 1184
Product of HCF and LCM = 1 × 1184 = 1184

(ii) 

HCF = 1
LCM = 46 × 51 = 2346
Product of two numbers = 46 × 51= 2346
Product of HCF and LCM  = 1 × 2346 = 2346

(iii) 

HCF = 3 × 5 = 15
LCM = 3 × 5 × 4 = 60
Product of two numbers = 15 × 60 = 900
Product of HCF and LCM = 15 × 60 = 900

(iv) 

HCF = 3 × 3 = 9
LCM = 3 × 3 × 2 × 7 = 126
Product of two numbers = 18 × 63 = 1134
Product of HCF and LCM = 9 × 126 = 1134
(v) 

HCF = 2 × 13 = 26
LCM = 2 × 13 × 3 × 4 = 312
Product of two numbers =  78 × 104 = 8112
Product of HCF and LCM  = 26 × 312 = 8112

Page No 23:

Question 1:

Choose the right option.
(i) The HCF of 120 and 150 is ................... .
(1) 30
(2) 45
(3) 20
(4) 120

(ii) The HCF of this pair of numbers is not 1.
(1) 13, 17
(2) 29, 20
(3) 40, 20
(4) 14, 15

ANSWER:

(i)
 
HCF = 2 × 3 × 5 = 30
Hence, the correct answer is option (1).
(ii)
40 = 2 × 2 × 2 × 5
20 = 2 × 2 × 5
The HCF of 20 and 40 is 2 × 2 × 5 or 20.
Hence, the correct answer is option (3).

Page No 23:

Question 2:

Find the HCF and LCM.
(i) 14, 28
(ii) 32, 16
(iii) 17, 102, 170
(iv) 23, 69
(v) 21, 49, 84

ANSWER:

(i) 

HCF = 2 × ​7 = 14
LCM = 2 × ​7 × 2 = 28

(ii) 

HCF = 2 × ​2 × ​2 × 2 = 16
LCM = 2 × ​2 × ​2 × 2 × 2 = 32

(iii) 


HCF = 17
LCM = ​17 × ​2 × ​3 × 5 = 510

(iv) 

HCF = 23
LCM = ​23 × 3 = 69

(v) 

HCF = 7
LCM = ​3 × ​4 × ​7 × 7 = 588

Page No 23:

Question 3:

Find the LCM.
(i) 36, 42
(ii) 15, 25, 30
(iii) 18, 42, 48
(iv) 4, 12, 20
(v) 24, 40, 80, 120

ANSWER:

(i) 

LCM = 2 × ​2 × 3 × 3 × 7 = 252

(ii) 

LCM = 2 × ​3 × 5 × 5 = 150

(iii) 

LCM = 2 × ​2 × 2 × 2 × 3 × 3 × 7 = 1008

(iv) 

LCM = 2 × ​2 × 3 × 5 = 60

(v) 

LCM = 2 × ​2 × 2 × 2 × 3 × 5 = 240

Page No 23:

Question 4:

Find the smallest number which when divided by 8, 9, 10, 15, 20 gives a remainder of 5 every time.

ANSWER:

LCM of  8, 9, 10, 15, 20 is given by

LCM = 2 × 2 × 2 × 3 × 3 × 5 = 360
Hence, 365 is the smallest number which when divided by 8, 9, 10, 15, 20 gives a remainder of 5 every time.

Page No 23:

Question 5:

Reduce the fractions 348319$\frac{348}{319}$ , 221247$\frac{221}{247}$ , 437551$\frac{437}{551}$ to the lowest terms.

ANSWER:

348319=348÷29319÷29=1211$$\begin{gathered} \frac{348}{319}=\frac{348÷29}{319÷29} \\ =\frac{12}{11} \end{gathered}$$
221247=221÷13247÷13=1719$$\begin{gathered} \frac{221}{247}=\frac{221÷13}{247÷13} \\ =\frac{17}{19} \end{gathered}$$
437551=437÷19551÷19=2329$$\begin{gathered} \frac{437}{551}=\frac{437÷19}{551÷19} \\ =\frac{23}{29} \end{gathered}$$ 

Page No 23:

Question 6:

The LCM and HCF of two numbers are 432 and 72 respectively. If one of the numbers is 216, what is the other ?

ANSWER:

Let the other number be x.
Now, HCF × LCM = Product of two numbers
⇒ 72 × 432 = x × 216
⇒x=72×432216$\Rightarrow x=\frac{72\times 432}{216}$
= 144
​Hence, the other number is 144.

Page No 23:

Question 7:

The product of two two-digit numbers is 765 and their HCF is 3. What is their LCM?

ANSWER:

HCF × LCM = Product of two numbers
⇒ 3 × LCM = 765
⇒LCM=7653$\Rightarrow \mathrm{LCM}=\frac{765}{3}$
= 255
Hence, the LCM of the two numbers is 255.

Page No 23:

Question 8:

A trader has three bundles of string 392 m, 308 m and 490 m long. What is the great est length of string that the bundles can be cut up into without any left over string?

ANSWER:

The greatest length of string that the bundles can be cut up into without any left over string is given by the HCF of 392, 308 and 490.

HCF = 2 × 7 = 14 
Hence, the greatest length of string that the bundles can be cut up into without any left over string is 14 m.

Page No 23:

Question 9:

Which two consecutive even numbers have an LCM of 180?

ANSWER:

Let us suppose the two consecutive even numbers be 2x and 2x + 2.
Now, product of two numbers = HCF × LCM
⇒ (2x)(2x + 2) = 2 × 180            (HCM of two even number is 2)
⇒ (x)(2x + 2) = 180  
⇒ 2x² + 2x = 180   
⇒ 2x² + 2x − 180 = 0
⇒ x² + x − 90 = 0
⇒ (x − 9)(x + 10) = 0
⇒ x − 9 = 0 or x + 10 = 0
⇒ x = 9 or x =  −10 (Neglecting)
Hence, the two consecutive even numbers are18 and 20.