2nd Class

     Introduction   All celestial body, including our earth comes in our universe. Earth and other planets, all revolve around the Sun. The Sun and its planets are called solar system. Planet in our solar system has one or more satellite which is called the moon of the planet. In this chapter we will study about our universe and solar system.            Our Solar System The sun is exactly at the center of our solar system and planets revolve all around the Sun. The closest planet from the Sun in our solar system is the Mercury, and the last planet is Neptune. Pluto is another planet which is no longer considered as a full planet. It is now called dwarf planet. There is also a region in our solar system which is populated with smaller more...

       Seasons   There are four seasons in India and they are given below:             Summer season This is a hot season. Summer stays from April to June. This is the season of sweating and scorching sun. Heat waves are common in this season. Therefore, light and cotton clothes are the most favorable clothes in summer season.              Rainy Season Rainy season comes after summer and it stays from July to September. This season is very necessary for agriculture because plants and crops need water to grow. But sometimes excessive rain causes flood and becomes reason of sufferings for human, plants and other living organisms.              Winter Season The months of November, December more...

       Temperature Unit for temperature measurement is expressed in degree Celsius. In the cold or winter season temperature is low. Higher temperatures are referred to as warm or hot weather conditions. Temperature or heat is measured by thermometer.              Which one of the following is measured in degree Celsius? (a) Temperature (b) Pressure cooker (c) Gas stove (d) Fire   Answer: (a) Explanation Temperature is measured in degree Celsius. Therefore, option (A) is correct and rest of the options is incorrect.       Which one of the following is used to measure temperature? (a) Kilometer (b) Meter (c) Thermometer (d) Inch   Answer: (C) Explanation  Thermometer is used for the measurement of temperature. Therefore, option (C) is correct and rest of more...

      Water   Water is the second most necessary requirement for the living organism. Living organism cannot survive without air for more than few minute. They also cannot survive without water for more than 3 days. Most part of our body is made up of water. Hence our body require water regularly because of excretion of waste water from the body.              Potable Water   Potable water is drinking water. This water is not polluted or contaminated and quality of this kind of water is high. Therefore, it can be used for drinking. If human and other living organisms do not get potable water they can suffer from waterborne diseases. Commonly water supplied in household is potable. People also use water purifier to make water potable. Persons who do not have access to potable water more...

       Pollution   Pollution means contamination of unwanted substances that causes harm to human and other living organisms. Various kind of pollutions are given below:             Air Pollution  Air get contaminated in such type of pollution because of the following: Various kind of smokes from industry, vehicles and other things. Excretion of living organisms at improper places, ' Filthy and garbage materials lying at improper places. Sneezing and breath of living organisms carrying diseases.   Look at the following picture of the cause of air pollution:                   Water Pollution Water bodies (Seas, oceans, rivers, lakes ponds and groundwater) get contaminated when: Garbage, dirty materials are thrown in the rivers, ponds, lakes etc. Industrial more...

      Germs in Air   Germs are very small or tiny organisms that can cause disease. They are so small that they creep into our bodies without being noticed and start causing troubles. Germs in the air take birth because of the air pollution.   The following are the reasons for germs in air or airborne germs: Various kinds of smokes from industries and vehicles. Garbage and filthy materials at improper places. Excretions of living organisms at open spaces. Any kind of offensive smells. Sneezing and breath of living organisms carrying various germs.           Which one of the following is true about germs? (a) They have the size of an apple (b) They have the size of an Orange (c) They have the size of a more...

       Usefulness of wind   The following are the uses of wind: It is very important for living things as they inhale air to be alive. Most of the living things inhale oxygen and exhale carbon dioxide. While Plants inhale carbon dioxide and exhale oxygen. It is very important for the growth of plants. Fresh and cool air is needed for living things to be energetic and active. Fresh and natural air makes a good environment. It is used for electricity generation. Wind is used to fill in balloons, football, wheels of buses, cars, cycles, motorcycles etc.             Living things cannot ———— without air. (a) Eat (b) Live (c) Drink   (d) See   Answer: (b) Explanation Living things inhale air to be alive. Therefore, option more...

     Types of Wind   Movement of air is called wind. There are mainly two types of wind depending on its motion. Global wind Local wind            Global Wind Global winds are the large movements of air that happen all over the world because of the following reasons; The rotation of the earth. The movement of the earth around the sun. Because of the round shape of the earth.            Local Wind Every region has their own type of winds. These winds are limited to that particular area and caused by temperature difference. They can move up, down and horizontal. Mountain areas are good example of such kind of winds. In these areas, wind blows against the mountain and is forced to go up. Because wind more...

     Introduction   Weather of a place is influenced by the condition of air and quantity of available water. Air is the mixture of different gases. Water is the chemical composition of hydrogen and oxygen. Both water and air is most important for living organism on the earth. Air always moves from high pressure area to low pressure area. This motion of air is called wind. In this chapter we will study about air, water and weather.        Air as a Mixture of Gases Air is not man made. It is a natural resource, and it is present everywhere. It cannot. be seen, and it is not exhaustible. Air is very important for living things because without air a living organism will die. This is the reason why air is called invisible friend of living organisms. Air more...

    Soil   Soil is a thin layer of earth's crust, which serves as a natural medium for the growth of plants. In fact, soil is a source of minerals for plants. Plants also get water via soil, which is necessary for their growth. As life of human and other living organisms is fully dependent on plants, soil is also very important for the life of living organisms.   Look at the following picture of different types of soil:                                              Clay soil                                             Sand soil                 more...