Move downwards During exhalation the ribs moves downwards causing a decrease in area of chest cavity forcing the air out.

Mercury is used as thermometric fluid because:
(i)It expands easily and uniformly on heating.
(ii)It can be used over a wide range of temperature.
(iii)It is easily visible, being opaque and shining.
(iv) It does not stick to the sides of a glass tube.

When the switch is in off position then the circuit from the positive terminal of battery to the negative terminal is not complete. The circuit is then said to be opened and current does not flow throughout the circuit and bulb does not glow.

During the condensation of water vapour and freezing of droplets, a large amount of heat is released which further pushes the air at a high speed. The water droplets and ice particles rub against each other in rapidly rising air. This builds up an electric charge which is released by a stroke of lightning.

Clouds are formed by the condensation of water vapours present in the atmosphere. It comes back to the atmosphere/earth as rain water. No new product is formed. So it is a physical change.

A simple pendulum has a small metallic ball called bob suspended from a rigid stand by a thread. The time taken by the pendulum to complete one oscillation is called time period. One oscillation of a pendulum is completed when the bob moves from position O to A and then from A to B and then back to A or from A to B to A.

Eight English alphabet letters which do not show lateral inversion are:
A, H, I, M, O, T, U, X.

To digest their food completely.

The excessive use of water leads to water scarcity in an area.

Asexually by vegetative propagation.

Frogs respire through their moist skin as well as through a pair of lungs

Low cost onsite sewage disposal system must be encouraged to improve sanitation.

Wool yielding animals are sheep, yak, llama, alpaca, angora goat, angora rabbit and camel.

In a forest, big trees, shrubs and other plants are found. They trap solar radiation for photosynthesis. So, the sunlight does not reach at the forest floor, thus making it dark.

The water in which these organisms live brings them food and oxygen as it enters their bodies.

The farmer can convert acidic soil into neutral soil by adding a small quantity of quicklime or slaked lime solution to the soil

Fungus produces antibiotics like penicillin used to treat diseases and fungus can also harm us by causing fungal infections on skin and hair.

Neutralisation reaction.

Adaptive features of penguin that help it in swimming are as follows
(i) It has streamlined body.
(ii) It has webbed feet.

(i) The cramps occur when muscle cells respire anaerobically. The partial break down of glucose produces lactic acid, accumulation of which causes muscle cramps.
(ii) Hot water bath improves circulation of blood. As a result, the supply of oxygen to the muscle cells increases and complete breakdown of lactic acid occurs to form carbon dioxide and water.
(iii) Apart from his profession Mr. Sharma is caring and conscious about his son, so he gave the perfect advice to him to get relief from fatigue.

Take a test-tube. Half fill it with cold water. Now drop in it a cube of ice wrapped in a wire gauze. It sinks to the bottom. Hold the top end of the test-tube with a test-tube holder. Heat it over a flame. It will be noticed that water starts boiling but ice is not fully melted. It means that heat has been transferred through the molecules of water. This shows that water is a bad conductor of heat.

An electric bulb is used for light but it also gives heat. This is not desirable. This results in the wastage of electricity. This wastage can be reduced by using fluorescent tube lights (CFLs)in place of the bulbs. CFLs are also used to reduce wastage of electricity. There are compact fluorescent lamps. These can be fixed in ordinary bulbs holders.

Due to spoilage of forest trees, the rainwater drops fall slowly on the ground. The forest also slows down the speed of rainwater and allowed it to seep. In absence of tress the rainwater hits the ground directly and may flood the area around it. Roots of forest trees bind the soil together and thus prevents soil erosion also.

(a) Fungus are non-green plants that grow on dead and decaying matter for their food.
(b) Fungus are also useful as it can cure different type of infections.
(c) Vivek is sincere, curious and knowledge with a keen sense of applying it where necessary.

Large scale deforestation has occurred to accommodate the growing population, to grow food for them and to provide space for industries. Vegetation slows down the flow of rainwater on land and increases the absorption of water by the soil.
Cutting down of trees and destroying vegetation, therefore interferes with the natural process by which seeping takes place and the groundwater is recharged.
It finally results in the depletion of the water table.

The main differences between asexual and sexual reproduction are

The ozone layer protects us from the harmful ultraviolet radiations which come from the sun. Ozone absorbs ultraviolet radiations coming from the sun and breaks down to form oxygen.
In this way, ozone layer absorbs harmful ultraviolet radiations.

Due to uneven heating of land and ocean water
In summer season The uneven heating of land and ocean water generates wind from the South-West direction. These winds carry lot of water from the Indian ocean.

The vertical section of heart shows that heart is divided into four compartments called as chambers.
(a) The upper two chambers of heart are called atria or atrium.
(b) The lower two chambers of heart are called ventricles.

The black sheep in the poem seems to have wool on almost all the parts as it in the poem, it offers wool enough to fill three bags full.

Image formed by the plane mirror shows lateral inversion, i.e. left seems to be right and vice-versa. In case of alphabetic letters A, H, I, M, 0, T, U, V, W, X, Y show same image in the plane mirror.

Type of salts
(i) Neutral salts e.g. sodium chloride (NaCI)
(ii) Acidic salts e.g. Ammonium chloride (NH₄CI)
(iii) Basic salts e.g. sodium hydrogen carbonate (NaHCO₃)

The difference between milk teeth and permanent teeth are

Soil formation is a slow process which occurs in following two steps
(i) Weathering of rocks is the breakdown of rocks into small particles by the action of air, wind and water.
(ii) These small particles mix with humus (organic matter) and form soil.

Polar regions Polar bear/penguin/ reindeer/musk oxen.
Tropical rainforests Red-eyed frog /elephants lion-tailed macaque/ lion and tiger.

(i) Water takes up heat from atmosphere to change into vapour. Next water vapour changes back to liquid raindrops and release heat in the atmosphere. This heat warms the air around and rises up causing a drop in pressure. This cycle is repeated that leads to very low pressure system with very high speed winds revolving around it. It is known as cyclone.
(ii) Particularly the East coastline of India is vulnerable to cyclones.
(iii) (a) Forecast and warning service.
(b) Construction of cyclone centres in cyclone prone areas.
(c) Rapid communication of warnings to the Government agencies, fisherman, ships and general public.
(iv) Tanay is an aware student and concerned about the incidents happening around him. He is a responsible future citizen of our country.

(i) Size of image of jug is 1cm.
(ii) Distance between image of jug and mirror is 5 cm.

(b) Carbohydrates and oxygen.
(c) Liberated-oxygen, Utilised-carbon dioxide.
(d) All plants cannot do photosynthesis, only green plants can do photosynthesis.

Water is needed for various life activities. If we continue the misuse of water and do not conserve it, the groundwater level will be depleted. This may result into various consequences like
(i) Lowering of the water table Excessive pumping can lower the groundwater table.
(ii) Reduced surface water supply Groundwater and surface water are connected. When groundwater is overused, the lakes, streams and rivers connected to groundwater, can also have little supply.
(iii) Loss of plants from land We fully depend on the plants for food directly or indirectly. Plants need water to prepare their food. If there will be scarcity of water on earth, the plants will be unable to prepare their food. This inturn will lead to the end of the life because world without plants means no food, no oxygen, not enough rain and other innumerable problems. Therefore, it is true that water is a precious resource

(a) The electric iron works on the basis of heating effect of electric current.
(b) The values showed by Pinki here is a great concern and love towards her own 4 years old daughter.

First of all, take a flat bottom flask and fix a rubber stopper having two holes in the mouth of the flask. Shift a thermometer through one hole and a glass tube with stopper through the other hole. Now, with the help of a vacuum pump, remove the air from the flask and try to record the temperature from the thermometer. Put a flask in the bright sunlight and we will observe that the thermometer records a rise in temperature. So, on this basis, we can say that this experiment proves that the heat radiation can travel through vacuum.

When the reproduction in an organism includes two types of gametes, i.e male and female from two different parents, it is called sexual reproduction, The sexual reproduction takes place by the fusion of male and female gametes by the process called fertilisation to form zygote.

Sexual reproduction (fertilisation) in plants The different steps that take place during sexual reproduction in plants are
(i) The pollens are deposited on stigma and begin to germinate.
(ii) Pollen tube containing male gametes reaches to the ovary of flower.
(iii) The tip of the pollen tubes gets dissolved and male gametes comes out of the pollen tube.
(iv) Inside the ovary male gametes fuse with the female gamete or egg present in the ovule.
(v) The fusion of both the gametes will result into a fertilised egg cell which is also called as zygote.

We can minimise waste and pollutants entering the water and create less wastewater by taking following few steps at home:
(i) By not throwing used tea leaves, solid food remains, etc., in the drain. We should throw it in the dustbin.
(ii) By not throwing chemicals like medicines, paints, insecticides, etc., in the drain as they increase the pollution load of the sewage

(a) Respiration is the process of breakdown of food to produce energy for performing various functions. It involves two major steps:
(i) Inhalation is the process of taking in of air which is rich in oxygen, inside our body.
(ii) Exhalation is the process of giving out of air which is rich in carbon dioxide from our body to the external environment.
(b) The number of times a person breathes, in a minute is called as breathing rate. An adult human being can inhale or exhale 15-18 times in a minute. It is the average breathing rate of an adult human being. Breathing rate is not constant always.

(a) Since, the graph between B and C is parallel to time-axis, so it indicates that Boojho is at rest.
(b) Since, the graph is not straight line, so it is a non-uniform motion.
\(Speed=\frac{Distance}{Time}=\frac{225-150}{12-8}=\frac{75}{4}=18.75\ m/min\)

(a) Neha's mother took a thread of natural silk fabric and another thread of artificial silk fabric and burn them separately. The thread which burns giving a smell of burning hair will be natural silk (or pure silk). The thread which burns giving a smell a burning paper will be an artificial silk.
(b) Yes, pure silk saree is more costly than an artificial one.
(c) Neha's mother is intelligent and knowledgeable.

(a) Sachin noticed the disturbance in the water cycle in his area like stream drying up. Pond water getting muddy, less availability of fuel wood, etc.
(b) Deforestation.
(c) Love for nature and environmental consciousness.

(a) Seawater is collected in shallow pits. It is then allowed to evaporate in the sun. As the water evaporates, the salt solution becomes supersaturated (concentrated). This supersaturated solution cannot hold the excess salt. Thus, it separates out in the form of salt crystals. These salt crystals are collected and are redissolved in water and filtered to remove insoluble impurities. The clear solution is again evaporated to obtain the crystals of pure salt.
(b) Salt is obtained from sea water by the process of evaporation.
(c) The values shown by Karan are curious, aware and intelligence

(a) Dialysis is the process used for cleaning of the blood by separating the waste products in an artificial medium.
(b) Dialysis is needed when the excretory organ of humans, i.e. kidney becomes damaged on unfunctional due to some injury or infection.
(c) Excretion process removes the waste products released in body after the utilisation of food and other components. These products are toxic and may harm us if not removed from our body.
(d) Kidney
(e) Priya is curious, sincere and aware eager to acquire new knowledge.

(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

China rose (gudhal) is an acid-base indicator.
China rose solution in different medium shows following changes:
China rose + acid \(\longrightarrow\) Give dark pink colour, hence A is an acidic solution.
China rose + base \(\longrightarrow\) give green colour, hence B is a basic solution.
China rose + neutral \(\longrightarrow\) No change in colour, hence C is a neutral solution.

(a) Table showing the reading of temperature from the graph:

(b) The highest temperature is seen on 3rd November, 2014.
(c) The lowest temperature or minimum temperature was seen on 06th November, 2014.