10th Class

  Metals and Non-metals   118 elements are identified of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. Metals and non-metals are characterized by their physical and chemical properties.   Characteristics of Metals

• Metals have tendency to lose electrons.
• Metals are strong and tough.
• Metals have high melting and boiling point.
• Most of the metals are malleable or can be changed into thin sheets. For example, aluminum can be drawn into thin sheets.
• Metals are ductile or can be drawn out into thin wires. For example, copper can be drawn into wire.
• Metals are good conductor of electricity and heat.
• Metals are solids at room temp except mercury, which is a liquid.
• Metals are lustrous.
• Metals tend to have low ionization energies. In other words they gets oxidized when they undergo chemical reactions.
• Metals form compounds more...

  Carbon and Its Compounds   We all are familiar with the black amorphous forms of carbon which are coal, charcoal and soot. Most of the things such as food, medicines, clothes, paper contain carbon. Carbon is the 6th element in the periodic table. All living organisms contain carbon. Carbon is also present in small amount in the earth's crust and in the atmosphere. Carbon is a tetravalent element. It can occur either in free state as diamonds, graphite and buckminster fullerene or in the combined state such as carbon dioxide, carbonates, coal, petroleum and organic compounds like carbohydrates, fats and proteins, etc.   Carbon has large number of organic compounds as it can form long chains of its own atoms. This is a unique characteristic that carbon element have among all other elements. This property to form long chains of its own atoms is called more...

  Periodic Classification of Elements   All the elements are divided into groups such that the elements in the same group have similar properties. The periodic classification of elements helps in systematic study of elements and makes it easy to understand the properties of elements.   Dobereiner's Triads Johann Wolfgang Dobereiner, a German scientist, was the first to classify elements. He grouped the elements with similar chemical properties into groups of three called Triads'. When elements were arranged in order of their increasing atomic mass, the atomic mass of the middle element was equal to the approximate arithmetic mean of the atomic masses of the other two elements of the triad. For example, Li, Na, K and Cl, Br, I.   Limitations of Triad Classification

• Large number of similar elements could not be grouped into triads. For example, iron, manganese, nickel, cobalt, zinc more...

  Life Processes   Life Processes There are some processes for obtaining nutrition, some help in procreating offspring. The processes which maintain body functions and are necessary for survival are called life processes.   Nutrition Nutrition is the process of intake of nutrients by an organism and the utilization of these nutrients. It is a substance that is obtained by an organism from its surrounding and used as a source of energy. Our body needs different types of nutrients in right amount. They are carbohydrates, fats, proteins, vitamins, minerals and roughage.   Mode of Nutrition                                                          Different organisms obtained their food in different ways. Thus the mode of nutrition among organisms is different. The following are the two modes of nutrition among the organisms:  

• Autotrophic mode of nutrition: In this mode of nutrition, an organism makes its own food with the help of more...

  Reproduction, Control and Coordination   All the organisms reproduce to continue their existence on the earth. The production of new organism from the existing organisms of the same species is called reproduction. It is a necessary process to maintain the life on the earth. There are several ways through which animals can produce offspring. The two main methods of reproduction are sexual and asexual.   Sexual Reproduction The production of new organism with the use of their sex gametes is called sexual reproduction. This type of reproduction requires two parents who donate genes to the young one, resulting in offspring with a mix of inherited genes. Humans, animals and many other organisms reproduce by this method. Many flowering plants also reproduce by this method.   Asexual Reproduction The production of new organism without the involvement of sex gametes is called asexual reproduction. In this type more...

  Heredity and Evolution   Heredity The transmission of traits from parents to their offspring is called heredity. It is the continuity of features from one generation to another generation.   Rules for the Inheritance of Traits: Menders Contribution The transmission of genetically controlled traits from one generation to another is called inheritance. Mendelian laws of inheritance states about the way certain characteristics are transmitted from one generation to another in an organism. Mendel used pea plants for his experiments. He studied the colour of flowers, their location on the plant, the shape and colour of pea pods, the shape and colour of seeds, and the length of plant stems. Mendel concluded that characteristics are transmitted from one generation to the next in pea plants.   Mendel's Laws of inheritance: Law I: Law of dominance - It states that when two homozygous individuals with one or more...

  Light and Human Eye   Light is an electromagnetic wave which do not require a material medium for their propagation. Light is composed of particles which travel in a straight line at very high speed. Light has a dual nature i.e. waves and particles. Speed of light is different in different mediums. Speed of light in vacuum is \[3\times {{10}^{8}}m/s.\]   Reflection of Light The process of sending back the light rays which fall on the surface of an object, is called reflection of light.     Rules for obtaining images formed by concave mirrors

• A ray of light which is parallel to the principal axis of a concave mirror, passes through its focus after refection from the mirror.
• A ray of light passing through the centre of curvature of a concave mirror is more...

  Electricity and Magnetic Effects of Electric Current   Electricity is the identity of modernity. It has really redefined the way of our life. Thus it has an important place in modern society. It is used almost at every place to facilitate modern activities.   Electric Current Electric current is the rate at which charge passes by a point in the circuit. The magnitude of electric current in a conductor is the amount of electric charge passing through a given point of the conductor in one second. The SI unit of current is ampere. A current of 1 ampere means that there is 1 coulomb of charge passing through a cross section of a wire in 1 second.   Electric Circuit Electric circuit is an incessant conducting path that consists of wires, electric bulb and switch between the two terminals of a cell or a battery more...

  Sources of Energy and Natural Resources   Energy is the capacity to do work. Without energy we cannot perform any activities. In our day to day life, we use energy from various sources for doing work.   There are mainly two categories of sources of energy: (1) Non-Renewable sources of energy (2) Renewable source of energy   Non-renewable Sources of Energy Are those sources of energy which cannot be quickly replaced when exhausted For example, fossil fuels, petroleum, etc.   Fossil Fuel It consists of mainly coal, petroleum and natural gas. It is a non-renewable source of energy. It takes millions of years for the formation of fossil fuels. It is formed deep under the earth from the remains of plants and animals. That's why fossil fuel should be wisely and carefully used. Fossil fuels have some disadvantages as well. It causes pollution to disturb more...

  Our Environment   The environment is the physical surrounding around us that includes biotic and abiotic components such as plants, animals, human beings, microorganisms, water, soil, air, etc. These all are interdependent and cannot survive without each other. Human being is the only organism who can cause imbalance in natural environment because of their greed. A balanced environment is necessary for the proper growth of all forms of life.   Ecosystem and Its Components An ecosystem consists of all the biotic factors such as plants, animals and microorganisms and abiotic factors such as soil, air and water, etc. In an area, these all factors function together. The following are the examples of ecosystems:

• Pond
• Forest
• Estuary
• Grassland

Ecosystem can be studied through the study of certain processes that link the living or biotic components to the non-living or abiotic components. The more...