PErIodiC TeAcHer

                       T he solid-state represents the physical state of matter in which the constituent molecules, atoms, or ions have no translatory motion although they vibrate about the fixed position that they occupy in a crystal lattice.                                               For characteristics, classification of solids read the following file: Day - 01 Solid-state

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As coronavirus continues its spread, panic-buying has swept store shelves of hand sanitisers. What's in these sanitizers and how effective are they in comparison to hand washing? This graphic takes a look.

When it comes to scoring good marks in board exams or entrance exams, most of the students waste their time to choosing the right study materials. Sometimes it may lead to failure because of the wrong selection of study material. NCERT have been responsible for the distribution and development of the books. These books helpful to secure comfortable score in exams.  Here you can find the exemplar questions without solutions. The same PDF file can be download from official website of NCERT. Class 12: 1. Solutions

Q 5.1. Distinguish between the meaning of the terms adsorption and absorption. Give one example of each. Ans: This phenomenon of attracting and retaining the molecules of a substance by a solid or a liquid on its surface resulting into a higher concentration of the molecules on the surface is known as adsorption. In absorption, the substance is uniformly distributed throughout the body of a solid or a liquid. Water vapours are absorbed by anhydrous calcium chloride but adsorbed by silica gel. For more questions Click on NCERT solutions

Use the following link to attend quiz: Quiz - 1 (Concentration terms)

                                                                    Subjective Questions 1.  Why is benzene soluble in toluene but not in water? Sol.  “ Like dissolves like”. Benzene and toluene are non-polar; H 2 O is polar. 2 . Explain, why solute-solute, solvent-solvent and solute-solvent interactions are important in determining the extent to which a solute dissolves in a solvent? Sol : In the dissolution process, solute – solute, solvent – solvent interactio n overcom e  and solute – solvent interactions are overcome and solute – solvent i nteractions are established. The solubility of a solute thus, depends on the strength of new solute – solvent interactions relative to the strengths of solute – solute and solvent – solvent interactions. 3. Indicate the type of solute – solvent inter molecular forces that should be most important in each of the following solutions: (a) KCl in water (b) C 6 H 6  in CCl 4 (c) HF in water (d) CH 3 OH in water (e) C

Identify the soluble compounds in water Solution s  of solids in solids (solid solutions) This type of solution is formed by mixing two solid components. For example, brass, bronze, monel metal and steel. Solid solutions are classified into two categories: substitutional solid solutions and interstitial solid solutions. l  Substitutional solid solutions  are formed by placing atoms of one kind into the place of other substance in its crystal lattice. Brass is a common example of the substitutional solid solution of copper and zinc. l  Interstitial solid solutions  are formed by placing atoms of one kind into the voids in the lattice of atoms of other substance. Tungsten carbide, an extremely hard substance, is a common example of interstitial solid solutions. S olubility  of solids in liquids  ( Saturated, unsaturated, supersaturated solutions) A solution which contains as much solute as it can be dissolve d  at a given temperature is called a saturated solution . S olubility - What do

“Catalyst is any substance which can change the speed of the reaction without being used up in that reaction and the phenomenon is known as catalysis.” For more information click on Catalyst

For a given solution, the amount of the solute dissolved in a unit volume of solution (or a unit amount of solvent) is termed as the concentration of the solute.   Solutions containing relatively high concentration of solute are called concentrated solutions while solutions of relatively low concentration of solute are termed as dilute solutions. The concentration of a solution can be expressed in a number of ways. For more information click the following: Concentration Terms

Finely divided particles of any substance with diameters lying within 1 - 200 nm dispersed in any medium constitute what we term a colloidal system.  A colloidal system is thus a two phase system consisting of a continuous phase or dispersion medium in which extremely minute particles, lying within the colloidal range, of second substance termed as discontinuous phase, are suspended. In this chapter you learn about classification, preparation and properties of colloidal solutions which are explained in the following video. Have a look !!!! https://www.youtube.com/watch?v=ljjAAAaypD8&t=26s

Introduction In normal life we rarely come across pure substances. Most of these are mixtures containing two or more pure substances. Their utility or importance in life depends on their composition. For example, the properties of Brass (mixture of Cu and Zn) are quite different from those of German silver (mixture of Cu, Zn and Ni) or Bronze (mixture of Cu and Sn); 1 ppm of Fluoride ions in water prevents tooth decay, while 1.5 ppm causes the tooth to become mottled and high concentrations of fluorides ions can be poisonous (for example, sodium fluoride is used in rat poison); intravenous injections are always dissolved in water containing salts at particular ionic concentrations that match with blood plasma concentrations and so on. Solution  - What does it mean? A true solution is defined as a perfectly homogeneous mixture of two or more substances   (called as components)  having uniform properties throughout and the composition of which may vary within limits. The substances by wh