The chest cavity is separated from the abdomen by a muscular wall called diaphragm. When diaphragm moves downwards and ribs move up and outward, the space in chest cavity increases. As a result, air from atmosphere rushes through nose, trachea to lung (inhalation or inspiration). When the diaphragm moves upwards to its original position, ribs move down and inward, the space in the chest cavity decreases. As a result, air from lung is forced out of the body through air passage (exhalation or expiration).

(i) The radiation of the Sun gives us heat which do not require any medium.
(ii) White colour absorbs less heat coming from Sun and more it reflects. The temperature of any object increases due to absorbed part of the heat, in case of white colour it is least.
(iii) Her mother preferred cotton clothes as they are light and porous through which air can pass easily and make our body cool, as the climate of Mumbai is temperate.

Thunderstorm develops in hot humid tropical areas. The rising temperatures produce strong upward rising winds. These winds carry water droplets upwards where they freeze and fall down again.
The swift movement of the falling water droplets along with the rising air crete lightning and sound. This event is called thunderstorm.

The wool obtained after shearing contains a substance called yalk which consists of complex chemical lanolin. In addition to it, the same wool contains suint, which is dried perspiration of sheep. These are removed by washing with soap-alkali preparation or some suitable detergent in tanks. This process is called scouring.

(i) Concave lens.
(ii) The image formed is erect, virtual and diminished.
(iii) The characteristics of the image will not change on changing the position of object.

We face shortage of water mainly because water is not evenly distributed by the nature on the earth. Some places such as North East India get so much rains, so that it gets flooded almost every year.
On the other hand, Thar desert in Rajasthan may get rains rarely in the monsoon season. This uneven pattern of rains causes water scarcity in India at some places.

First sedimentation tank.

The steps involved in the process of fertilisation are
(i) After pollination, pollen grains start growing into a pollen tube on the stigma passing through pistil.
(ii) The tube extends through the style and reaches to the ovules.
(iii) The pollen tube carries the male gametes called pollen grains.
(iv) Male gametes fuse with the egg (female gamete) present inside ovule and forms a zygote. This process is called fertilisation.
(v) Later zygote develops into an embryo and ovules develop into a seed.
(vi) Thus, seed carries an embryo with stored food and is covered by a hard protective covering called seed coat.

After studying the figure given alongside, 0 or E is moving slower as the slope of distance-time graph of E is less than that of graph D.

Photosynthesis is the process during which CO₂ is used by the plants and O₂ is released as a products. This O₂ is used by the animals for their respiration and CO₂ is released during it which is again used for photosynthesis by plants. In this way, O₂ - CO₂ cycle is balanced by plants.

In human, the heart has four chambers. The two upper chambers are called the atria and the two lower chambers are called the ventricles. The partition between the chambers helps to avoid mixing up of blood rich in oxygen with the blood rich in carbon dioxide.

Burning of wood is a chemical change while cutting of wood is a physical change because, during burning, new substances are formed. After burning, we cannot get original substance (i.e. wood) back. Cutting of wood into small pieces is a physical change because no new substance is formed.

In dense forests, the tree cover (canopy) prevents rainwater from directly falling on the ground/soil. Also roots of the vegetation bind the soil particles and hold them together. As a result, soil erosion is minimised. But in barren, open fields, the soil is exposed to the falling rain. The soil particles become loose due to the impact of raindrops and the flow of water carries them away. The flowing water further erodes the soil surface aggravating erosion.

Green plants are the source of energy for all the living organisms so that they can perform their normal functions. If all green plants and trees disappear, all the organism depending on them for food and shelter will also die.
The lack of gaseous exchange will lead to increase in amount of CO₂, causing death in humans and other animals also. The cycle of life will gradually disappear.

Polar bear have white fur. This is an adaptation of polar bear to blend it with the white background of ice or snow. This helps them to protect from their predators and also to catch their prey.

Differences between acids and bases are as follows:

The handles of most utensils are made of plastic and wood because plastic and wood are poor conductors of heat. We can easily hold the handle with bare hands even if the utensils are hot. This helps us to remove hot utensils from the flame.

The air contains spores of bread mould which can survive in air for long time due to presence of a thick wall. When they fall on a piece of moist bread they germinate on it.

MCBs (Miniature circuit breakers) are switches which automatically turn off when current in a circuit exceeds the safe limit. We turn them on and the circuit is once again complete

15-18 times.

The trees have crowns of different sized and types. These create different horizontal layers in the forest. These are known as understoreys. Giant and tall trees constitute the top layer followed by shrubs and tall grasses and herbs form the lowest layer.

Sand clock is a clock used by Romans to measure a constant time called hour. It consists two chambers fitted over one another filled with an amount of sand and it takes exactly one hour to empty a chamber. Once the upper chamber is completely emptied, the chamber is turned upside down to record the time again. It is also called hour glass

Take some turmeric and mix it in some water to make a paste. Deposit it on blotting paper of filter paper and dry it. Cut thin strips of the yellow paper so obtained. These thin strips are turmeric paper

Basically it is used in making silk fibres

The major surface area (71%) of the earth is covered with water. This imparts blue colour to the earth.

Fruits and vegetable wastes, pesticides and herbicides are organic impurities present in sewage other than animal wastes, oil and urea.

It is because the winds would have blown in the North-South direction either from North to South or from South to North. A change in direction is however caused by the rotation of the earth.

Concave mirror is known as a converging mirror because it converges a beam of parallel rays of light (reflecting from it) at one point.

Ripening of a fruit is a chemical change because after ripening, a new product with different properties is formed.

Arteries carry blood at a very high pressure due to pumping action of heart hence, the need of thicker walls.

The absorption percentage of water can be calculated by the formula given below
Percentage of water absorb
\(\frac { amount\quad of\quad water\quad absorted(in\quad ml) }{ amount\quad of\quad soil(in\quad gm) } x100\)

The function of mucus is to protect the lining of stomach from the action of hydrochloric acid secreted by stomach lining.

Leaves are referred to as food factories of plants. This is because, leaves synthesise food by the process of photosynthesies.

Those animals that can live both in water and on land are called amphibian, e.g. frog.

(a) Wastewater is passed through bar screens. Large objects like rags, sticks, cans, plastic packets, napkins are removed.
(b) Water then goes to a grit and sand removal tank. The speed of the incoming wastewater is decreased to allow sand, grit and pebbles to settle down.
(c)The water is then allow to settle in a large tank which is sloped towards the middle. Solids like faeces settle at the bottom and are removed with a scraper. This is the sludge. A skimmer removes the floatable solids like oil and grease. Water so cleared is called clarified water. The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria. The biogas produced in the process can be used as fuel or can be used to produce electricity.
(d) Airis pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water.
(e) After several hours, the suspended microbes settle at the bottom of the tank as activated sludge. The water is then removed from the top.

The reasons of depletion of water table:
(1) Increase in population.
(2) Industrialisation.
(3) Agricultural activities.
(4) Scanty rainfall.
(5) Deforestation.
(6 Decrease in the effective area for seepage of water.
Effect of increasing population:
As the population increases, demand for construction of houses, shops, offices, roads and pavements is increased. This decreases the open areas like parks and playgrounds. This in turn decreases the seepage of rainwater into the ground. More over a huge amount of water is required for construction work. Often groundwater is used for this purpose.
So, on the one hand we are consuming more groundwater and on the other hand we are allowing less water to seep into the ground. This results in the depletion of water table.

The disaster management of a cyclone involves:
(A) Effective Safety Measures:
(i) A cyclone forecast and warning service.
(ii) Rapid communication of warning to the government agencies, the ports, fisherman, ships and to the general public.
(iii) Construction of cyclone shelters in the cyclone prone areas and administrative arrangements for moving people fast to safer places.
(B) Action on the Part of the People:
(i) We should not ignore the warnings issued by the meteorological department through media like TV, radio or newspapers.
(ii) We should:
(a) make necessary arrangements to shift the essential household goods, domestic animals and vehicle etc., to safer places.
(b) avoid driving on roads through standing water, as floods may have damaged the roads and
(c) keep ready the phone numbers of all emergency services; like police, fire brigade and medical centre. Some other precautions if you are staying in a
cyclone prone area:
(1) Do not drink water that could be contaminated. Always store drinking water for emergencies.
(2) Do not touch wet electric switches and fallen powerlines.
(3) Do not pressurise the rescue force by making undue demands.

If we leave a piece of iron in the open for some time, it acquires a coating of brownish substances. This substance is called rust and the process of its formation is called rusting. This is the change that effects iron articles and slowly destroys them. Since iron is used in making bridges, ships, cars, truck bodies and many other articles. The monetary loss due to rusting is huge. For rusting the presence of both oxygen and water (or water vapour) is essential. Infact, if the moisture content in air is high which means if it is more humid, rusting becomes faster.
Methods of preventing rust formation: Rusting of an iron object can be prevented or reduced by not allowing air and moisture to come in contact with the surface of iron objects. Following are the methods of prevention form rusting.
(i) Putting oil or paint over the surface of iron implements.
(ii) Galvanization: In this method, surface of iron is covered with a layer of more active metal like zinc. Zinc metal looses electrons in preference to iron and hence, prevents the rusting of iron.
(iii) By tin-plating 
(iv) Use of anti-rust solutions: Alkaline chromate and alkaline phosphate solution act as anti-rust solutions. When iron objects are dipped into a boiling and strongly alkaline solution of sodium phosphate, a protective insoluble film of iron phosphate is formed on them. This film protects the article form rusting.

Fibres and fabric play a large role in everyday application. A fibre is a hair-like strand of material. They are the smallest visible unit of a fabric and denoted by being extremely long in relation to their width. Fabric can be spun into yarn and made into fabric.A single fibre is too week to break but when it one made a fabric it is difficult to tear. Fabric needs more energy to tear apart as compared to single fibre.

All changes in the weather are caused by the sun. The energy sent out by the sun is so huge that it is the source of all heat and light on the earth. Energy absorbed and reflected by the earth surface, oceans and the atmosphere play an important role in determining weather of any particular place.

The food of ruminants like grass is rich in cellulose (a type of carbohydrate). Ruminants have a large sac-like structure between the small intestine and large intestine. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans. In this way ruminants can digest the cellulose but many animals including human can not digest cellulose. 

(a) No, the amount of heat produced in both the wires will be different because amount of heat produced in a wire on passing electric current depends on the length of wire and here length is different for both the wires.
(b) No, the amount of heat produced in the wire of same length but different thickness cannot be same because amount of heat produced in a wire also depends on the thickness of the wire.

(a) The following precautionary measures while checking the fever through a clinical thermometer are
(i) While reading the clinical thermometer, it should never be held by the bulb.
(ii) The clinical thermometer should be washed properly (before and after use).
(b) The values showed by the elder brother of Pankaj, Vishwas, are concern towards the way of using the clinical thermometer and the importance of money as well.

(a) Vegetative propagation is the process of reproduction in which new plants are produced from different parts of old plants like stem, roots or leaves.
(b) Cutting and grafting method are two methods where stem is used for vegetative propagation.
(c) Mango and rose are two plants cultivated using vegetative propagation.
This is an asexual method of reproduction.
(d) Ria is curious, inquiring who wants to gain knowledge about process occurring around here.

The fishes have special type of organs for respiration called gills. These gills absorbs oxygen dissolved in water and through blood vessels, this oxygen is passed to all the parts of the body. The amount of dissolved oxygen is comparatively less in water than the amount of oxygen in air. Therefore, the rate of breathing is also high in aquatic animals.
If we add warm water, to the aquarium the dissolved oxygen will dissociate and move into the atmosphere again, leaving the least percentage of oxygen into the water (as it is known that the solubility of gases in water goes down as the temperature rises). Therefore, fishes will have difficulty in breathing in the absence of oxygen and will die.

(a) Convex mirror is a mirror which is used as a rearview mirror. It is used to get a wide view of traffic behind.
(b) The values exhibit by Namit here is courtesy concerned for other, sympathy, knowledgeable.

(a) From the graph, it is clear that the distance at 20 s is 8 m.
(b) Distance travelled by the body object in 12 s is 6 m.
(c) \(Average\ speed=\frac{Total\ distance}{Total\ time}=\frac{8}{20}=0.4m/s\)

Forests maintain balance in nature. There conservation is the need of the hour. We should take the following steps to conserve the forests.
(i) Planned harvesting An efficient way to get wood from forests for our requirements is to cut only some of the trees in an area. The uncut trees prevent erosion. Fruits of these trees produce seeds so that new trees can grow. This way the forest cover is maintained.
(ii) Afforestation This is the practice of renewing a forest by planting seedlings or small trees. These days, in our country, planned afforestation is being done not only by the government but also by private organisations for commercial purposes. Selective cutting of trees in these plantations provides wood for construction and also keeps the forest cover intact.
(iii)Protection from fire Huge forest areas are destroyed by fire every year. Fire may occur due to the carelessness of people or due to lightning during a storm or by friction between dry stems and dry branches of trees.Forest fires are controlled by spraying fire extinguishing solutions from aircrafts or by changing the direction of wind by using strong blowers.

(a) When a cut or wound starts bleeding after some time, a clot is formed which plugs the cut and bleeding stops.
(b) Wounded area becomes dark red in colour due to clotting of blood.
(c) The blood clot is formed due to the presence of the cells called platelets in the blood.

(a) An earthworm helps in making the rich humus in soil.
(b) Ant, earthworm, termites, milipede, centipede, etc.
(c) Curiosity to learn and scientific attitude

The process by which green plants can prepare their own food is called photosynthesis. Green plants possess chlorophyll in their leaf and utilises carbon dioxide (from air) water, minerals (from soil, through root) as raw material and sunlight as source of energy and convert light energy into chemical energy. The food thus synthesied is in the form of starch (carbohydrate). The overall reaction for photosynthesis can be given as follows:

(a) The reason for this burning pain is honeybee sting which causes pain and irritation. This is due to the acidic liquid (formic acid) injected into the skin by the honeybee.
(b) The effect of acid can be neutralised by rubbing the affected area by baking soda solution which is a mild base.
(c) Nitesh's friends are caring, supportive and helpful.