new construction pa

Join AB. Locate O the mid point of AB. Join PA and PB. Join P and ..

Based on the positions in the periodic table, Mendeleev could predict the properties of some undiscovered elements. He left three blanks for elements that were not discovered at that time. He was able to predict the properties of these unknown elements more or less accurately. He named them eka-bo..

2, 5, 8, 11, 14 , 32 37, 33 , 1 A sequence is called infinite if the number of terms is infinite. An infinite sequence has no last term. In this sequence, every term is followed by a new ter..

Chemical reactions are the processes in which new substances with new properties are formed. A chemical reaction should satisfy the following conditions: There must not be either a gain or loss of matter. There must be either an evolution or an absorption of heat i.e. an en..

The criterion for a chemical change is the production of one or more new substances. Therefore, certain conditions should be met in order to bring about a chemical change. The necessary conditions are: 1) A minimum amount of energy needed to initiate a reaction (activation energy) should ..

Introduction - In the chapter on current electricity, we had learnt about the flow of charges, conditions to produce the flow and how different materials respond to an external electric field. We had seen how materials are classified as conductors and insulators. In this chapter, we will study a ..

A physical change is one in which the shape, size, appearance or state, of a substance may alter, but its chemical composition remains same. No new substance is formed. It is usually a change, which is reversible. By reversing the process, the original substance can be obtained. Exa..

Solar cells are expensive and are used only when supplying electricity becomes difficult. Solar cells are the devices where solar energy is directly converted into electricity. Solar cells are used in spacecrafts, radios, television, refrigerators, buoys and other navigation aid. Solar Cell Sunligh..

A change in which the composition of a substance is altered is called as chemical change. As a result, the original properties get changed and one or more new substances are formed. Iron is a greyish white metal and conducts electricity. It is attracted by a magnet, and reacts with ..

The following rays are usually considered while constructing ray diagram..