CBSE ADDA

Mole Concept we can express the quantity of a substance is expressed in terms of mole. Mole is a fundamental unit in the System International d' Unités, the SI system, and it is used to measure the amount of substance In Latin mole means a "massive heap" of material Mole is defined as the amount of substance that contains as many specified elementary particles as the number of atoms in 12g of carbon-12 isotope . One mole is also defined as the amount of substance which contains Avogadro number (6.023 x 1023) of particles. Avogadro number: Number of atoms or molecules or ions present in one mole of a substance is called Avogadro number. Its value is 6.023 x 10 23 Therefore, one mole of any substance contains Avogadro number of particles. The particles may be atoms, molecules, ions etc E.g. 1 mole of oxygen atoms = 6.023 x 10 23 atoms, molecules, ions etc  of oxygen                                                = 32g of O 2 Problems (based on m

chemistry adda: Electronic Configurations of elements in periodic ... : 1 - Hydrogen: 1s1 2 - Helium: 1s2 3 – Lithium: [He], 2s1 4 – Beryllium: [He], 2s2 5 – Boron: [He], 2s2, 2p1 6 – Carbon: [He], 2s2,...

Chemical and chemical reaction Acid Base and Salts Metals and Non Metals Periodic Classification of Elements For more  http://jsuniltutorial.weebly.com/science1.html

Trigonometric Ratios of 30 0 and 60 0 Let D ABC be an equilateral triangle whose sides have length a Draw AD ^ BC, then D bisects the side BC. So, BD =  DC=  a/2 and < BAD = < DAC = 30 0 . Now,  in right triangle ADB, < BAD = 30 0 and BD=  a/2 So, AB 2 =   AD 2 +  BD 2 a 2   = AD 2 + (a/2) 2 AD  = √ 3/2 a   Hence, we can find the trigonometric ratios of angle 30 0 from the right triangle BAD