Climate and Weather
Climate has a great effect on all the living organisms. Record of weather at a particular place is preserved for long period of time (30 years), which is known as the climate of that place. If observation of temperature of the particular place is high, we say that the climate is hot and if low temperature is recorded then climate is cold.
There are four types of climate in the world. These are polar climate, temperate climate, tropical climate and desert climate.
Polar region receives less amount of solar energy from the Sun, therefore, climate is cold in the polar region.
Look at the following picture of the polar region
The weather in the temperate climate is neither too hot in summer and nor too cold in winter.
Weather in the tropical climate is very hot. The rain fall is usually high in the tropical climate. Therefore, high humidity is recorded.
Weather in the desert climate is recorded very hot and dry. The rain fall in the desert is very little.
Weather affects the life of living organisms, which is dependent on the heat of the Sun. The hotness of the air depends on the strength of the solar radiation.
Air is heated by the solar radiation. Amount of water vapor present in the air is called humidity. Humidity of air is expressed in percentage. A humidity of 100% at a particular temperature means that air is saturated with water vapor. Rainfall is measured by an instrument called rain gauge and it is measured in millimeters.
Thermometer is used for the measurement of the temperature. The minimum and maximum temperature is recorded in a day.
Which one of the following climate is very cold?
(a) Polar climate
(b) Temperate climate
(c) Desert climate
(d) Tropical climate
(e) None of these
Answer: (a)
Maximum rain fall is recorded in which one of the following climate?
(a) Tropical
(b) Temperate
(c) Polar climate
(d) Desert climate
(e) None of these
Answer: (a) 
Adaptation of Animals in Different Climate The presence of specific body features, which enable an animal or a plant to live in a particular habitat, is called adaptation. Migration of the birds protects them from extreme cold and hot climates. Siberian crane is a migratory birds, which come every year in India, during winter. Look at the following picture of penguins and polar bears
Fig. (1) Penguins Fig (2) Polar bear
Penguins cannot fly but they can swim by their flippers. Penguins live in the extreme cold climate of south Polar Region. Thick skin of penguins and the layer of fat under their skin protect them from extreme cold weather. Penguins huddle together to keep themselves warm. They eat fishes. Polar bear is another animal who lives in polar region. Fur over the skin in the body of polar bears protect them from extreme cold. The layer of fats over the body protect them from temperature loss. They eat fish.
Penguins live in the polar region. Which one of the following body features protect them from extreme cold?
(a) Flipper
(b) Denser fur over the skin
(c) Layer of fat under the skin
(d) All of these
(e) None of these
Answer (c)
Which one of the following is true about the penguins?
(a) They live in the desert place
(b) They eat grasses
(c) They live in polar region
(d) All of these
(e) None of these
Answer: (c) 
Pollution
There are various polluting elements which are causing pollution in our environment. The most common causes of the land pollution is the dumping of waste materials. Polythene, plastic metals, glass etc. pollute the soil. The use of pesticides is also a major cause of soil pollution. Pesticides are the chemicals used for the protection of crops from harmful bacteria. Pesticides enter in the soil thereby polluting it. Fertilizers are also made from chemicals (acid and alkalis). The excess presence of chemicals in the soil is resulting in soil pollution. Acid rain also cusses the soil pollution. Acid rain occurs due to the air pollution.
Look at the following picture of soil pollution
Which one of the following is a major cause of soil pollution?
(a) Excess use of fertilizers
(b) Excess use of compost
(c) Excess use of land for crops
(d) All of these
(e) None of these
Answer: (a)
Mixing of unwanted substances in the air is called?
(a) Soil pollution
(b) Land pollution
(c) Air pollution
(d) All of these
(e) None of these
Answer: (c)
The Earth is the third planet and only one capable of supporting life in the solar system.
The Earth consists of three main layers, crust, mantle, and core.
Weather in the tropical climate is very hot and therefore high humidity is recorded.
Rainfall is measured by an instrument called rain gauge.
The excessive use of fertilizers causes soil pollution.. 
Salt and its Types
Salt is formed by the reaction of an acid with a base. Sodium chloride is formed by hydrochloric acid and sodium hydroxide base. The salt is prepared by the reaction of strong acid with weak acid. The salts of hydrochloric acid are called hydroxide and the salts of sulphuric acid are called sulphate. The salts of nitric acid are called nitrate. The salts of carbonic acid are called carbonates and the salts of acetic acid are called acetates.
There are three kinds of salt that is, natural salt, acidic salt, and basic salt. The salt, which form a neutral solution on dissolving into water are called natural salt. I.e. sodium chloride 
and sodium sulphate
. Natural salt does not have effect on litmus paper and the colour of litmus remains unchanged in the solution of natural salt. The salts, which form an acidic solution on dissolving into water are called acidic salt. i. e, ammonium chloride 
and ammonium sulfate. Litmus paper turns blue to red in the solution of acidic salt. The salts, which form a basic solution on dissolving into water are called basic salt. i.e., sodium carbonate 
and sodium hydrogen carbonate
. It turns red litmus into blue.
Uses of Salt
Salts are commonly used in the various industries. In the aluminum refining, salt is used for the removing of impurities. In the process of rubber manufacturing, salt is used for separating the rubber form latex. In the pharmaceutical industries, salt is used for polishing the tablets. In the soap manufacturing industries, salt is used to separate the glycerin from water. Salt is used to preserve the food. The color of salt is white. Different colour that a salt may show is due to impurities.
The salt, which form a neutral solution on dissolving into water are called neutral salt. Choose the neutral salt from the following?
(a) Nitrogen sulphide
(b) Sodium chloride
(c) Ammonium chloride
(d) Ammonium sulphate
(e) None of these
Answer: (b)
Salt is formed when:
(a) Acid reacts with base
(b) Acid reacts with acid
(c) Base reacts with base
(d) All of these
(e) None of these
Answer: (c)
Indicators are used to identify the nature of the substances.
Litmus is commonly used to identify the acids and bases.
Litmus is obtained from lichen.
Indicators remain unchanged in salt.
Acid furnishes ions on dissolving in water. 
Uses of Acid and Base
Acids are used in the laboratory and industries for various purposes. Nitric acid is used to increase the fertility of the agriculture land, like, ammonium nitrate, calcium ammonium nitrate, etc. Nitric acid is also used in explosive. It is used for the washing of precious metal like, gold and silver. Sulphuric acid acts as a reactance in the manufacturing of fertilizers, like ammonium sulphate, super phosphate. It is used in refineries, car batteries, and in chemical reactions. Hydrochloric acid is used for bleaching in the textile industries, and it is also used for the purification of salt. Basic solutions are also very useful for us. Antacid is used for relaxation from the acidity. Antacid is a basic solution and known as milk of magnesia or magnesium hydroxide. A bitter taste is the characteristics of the all bases. Ammonium hydroxide is a cleaning agent. Calcium hydroxide is widely used in the preparation of plaster and mortar. Wafer solution, of calcium hydroxide also called lime water, is used in the laboratory for the testing of presence of carbon dioxide.
Calcium hydroxide is used for the preparation of plaster and mortar. It is known as;
(a) Pure water
(b) Lime water
(c) Cold water
(d) Hard water
(e) None of these
Answer: (b)
Which one of the following is also known as magnesium hydroxide?
(a) Copper
(b) Paintids
(c) Antacid
(d) Thermocoal
(e) None of these
Answer: (c) 
Method of Testing Acid and Base
The testing of acid is done by indicators, i.e. litmus.
Testing of Add
It requires two litmus, two beakers and the solution of acid and base. The nature of substance, whether it is acidic or basic is obtained from the colour of litmus. The blue color of litmus turns into red, if the solution ,s acidic. The red color of litmus turns into blue, if the solution is basic.
Look at the following picture of testing of Acid
Blue litmus turns to red Red litmus turns to blue
All acids are aqueous solutions and conducts electricity. The dry cell is filled with acid. It is present inside the small chamber of the cell. The high capacity of battery is also made up of acid. Positive ion of an acid acts as the positive is terminal of the battery and negative ion acts as negative terminal of the battery.
Look at the following picture:
Acid filled jar (A) Base filled jar (B)
In the above picture, jar (A) has acid and an electrical bulb is connected in series. Conducting rod inside the jar is used as a switch. Positive terminal of battery is connected to one end of the bulb and negative terminal of battery is connected to a conducting rod. Another end of the bulb is connected to another rod. Bulb starts glowing, when both rods are into acid and they are not in contact with each other. Therefore, it is clear from the above experiment that current flows through acid.
Read the following about the common indicators and its colour in acid:
| Indicators | Colour in acid | |||
| Blue litmus | Red | |||
| Methyl orange | Orange | |||
more...
 Concentrated and Diluted Acid
The substance, which has hundred percent of acid is called concentrated acid. It completely dissolves in water and furnish ions.
The concentrated acid is also called strong acid. The acid, which has lower percent of acid is called diluted or weak acid. Dilute acid is not a pure form of acid, during the chemical reaction its performance is slower than the concentrated acid. It does not dissolve completely in water or furnish ions. In the following chemical reaction, carbon dioxide reacts with water and gives hydro carbonic acid. This is the weak and diluted acid.
Acids can be categorized into three main types, natural acids, mineral acid and organic acid. Natural acid is obtained from plants. The sources of citric acids are lemon and orange. Apple contains malic acid. Tomatoes are the big sources of oxalic acid. Milk is the source of lactic acid. Tea is the source of tannic acid. Vinegar is the source of acetic acid. Vitamins are the sources of amino acid. The acids prepared from the minerals are called mineral acid.
These are sulphuric acid  , nitric acid  and hydrochloric acid . Organic acid is obtained from plant and animal. The juice, which is obtained from plant and animal are mostly diluted acid because of the presence of water.
Some strong or concentrated acids are: Hydrochloric acid, sulphuric acid, nitric acid and phosphoric acid.
Some weak or diluted acids are: citric acid, acetic acid, carbonic acid, tartaric acid.
 Every fruits contain acid. The acid found in fruits is called
(a) Strong acid
(b) Weak acid
(c) Mixed acid
(d) All of these
(e) None of these
Answer: (b)
 The formation of add by the chemical reaction of carbon dioxide and water is called?
(a) Strong acid
(b) Dilute acid
(c) Basic acid
(d) Sulphuric acid
(e) None of these
Answer: (b)  Indicators
Indicators are used to indicate the nature of a substance. Chemical compounds have been categorized into three groups, that is, acid, base and salt, according to their nature. The substance whose nature is acidic (sour in test), called acid and whose nature is basic (bitter in test) is called base. Litmus is the natural indicator and used for the testing of the solution. Litmus paper turns blue to red if the solution is acid, and it turns red to blue if the solution is base. Litmus paper is widely used in the chemical laboratory.
Look at the following picture of Litmus
 
Acid Base
The natural colour of litmus is purple. Litmus is obtained from a type of tree called lichen. The colour of the natural litmus is converted into red and blue for the application in chemical experiment.
Look at the Following Picture of Lichen (Source of Litmus)
Phenolphthalein is a solution used as an indicator in the chemical laboratory it is a synthetic indicator. Colour of phenolphthalein does not change in the acidic solution, while in the basic solution it turns into pink colour
Look at the Following Picture of Phenolphthalein in Indicator
In the above picture, there are three beakers, one has phenolphthalein. If we Put a drop of acid into it, the colour of does not change. But if we put a drop of base into it, the color of indicator turns into pink. Again a drop of acid into the pink colored beaker turns it colorless- Acid cancels the effect of the basic component. The substance whose colour does not change in any solution of indicator is called neutral substance. The ch.na rose is also used as the indicator and called natural indicator Acids turn china rose indicator into magenta (deep pink). Bases turn China rose indicator into green. Another indicator is turmeric paper. In the acidic solution it turns into yellow. In the basic solution, it turns into red. Ph value is used to show the nature of the solution.
|
Thermo Flask
Look at the given picture
1- Screw on top
2 - Outer cover is of plastic or steel
3 - Outer layer is of glass or steel coated
4 - Vacuum
5- Inner layer is of glass or steel coated
6 - Support
7 - Additional insulation reduces heat loss
Thermo flask is used for keeping a liquid in its original form. A glass of hot water in a thermo flask remains hot long time due to it’s built up. A screw part on its top is used for inlet or outlet. It also protects liquid from lay down. Heat, produced by the hot liquid does not radiate. External heat or cold does not absorb by the liquid. Plastic and lead inside the flax is the poor conductor of heat therefore, these are used for the making of flask. Steel body inside or outside of the flask reflects heat. Liquid inside the flask remains in its state due to convection of heat. The outer surface of the flask reflects radiant heat. The insulation between the outer surface and inner surface of the flask provides extra insulation.
The inner and outer surface of the flask is coated with plastic and steel. Why heat does not appear at the outer surface of the flask, if flask contains hot liquid?
(a) Due to conduction between inner and outer surface
(b) Due to insulation between inner and outer surface
(c) Due to radiation between inner and outer surface
(d) Due to convection between inner and outer surface
(e) None of these
Answer: (b)
Which one of the following is an insulator of heat?
(a) Copper
(b) Iron
(c) Steel
(d) Thermo coal
(e) None of these
Answer: (c)
Units of temperature measurement are, Celsius, Fahrenheit and Kelvin.
Shiny and smooth objects reflect more light as compare to rough surface.
Heat travels by conduction, convection and radiation,.
Thermal expansion of gas is measured at constant pressure.
Thermo flask is used to store hot liquid. 
Absorption of Radiated Heat
Every object absorbs more or less heat from atmosphere or from other heat producing sources. If we put anything in the sunlight, after some time it gets heated. The amount of heat to be absorbed by a body depends on its heat absorption capacity. It also depends on the amount of heat produced by the body. On the surface of the Earth, various colors are available. The heat absorption capacity of every object depends on its color also. Black color absorbs more heat than oth.er colors. White color reflects more heat than others. The objects having dark color absorb more radiated heat than the objects of light color.
In the figure below, there are two coffee cans taken for an experiment to show the absorption of radiant energy. Thermometers inside the coffee are used for the measurement of temperature. Now paint the coffee can by white and black color. After some time, we will see that the reading of the thermometer, which has been put inside the black coffee can, is increased. The thermometer inside the white coffee can will also show an increased reading, but it is very low in comparison to that of black polished coffee can. This experiment proves that the black colour of coffee has absorbed more heat than the white one.
Look at the following picture of absorption of heat energy
People prefer to wear white colour during the hot summer session, as the white color of the clothes reflect more heat than other colours. Our house should be painted with light color, because it reflects more heat and protects us from warm summer session. Absorption of heat by the solar cooker is used to cook the food. The inner surface of the water heater is painted with the black colour because of its good absorption capacity of heat.
Which one of the following colours is good but a poor absorber of heat?
(a) Blue
(b) Red
(c) Light color
(d) Dark color
(e) None of these
Answer: (c) 
