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Answer - 1.   When H 2 S is passed through cadmium chloride solution, yellow precipitate of cadmium sulphate and hydrochloric acid solution are obtained. 2.   The reaction is a double displacement reaction.

Answer - When oxidation and reduction take place simultaneously in a given chemical reaction, it is called redox reaction or oxidation-reduction.

Answer - When oxidation and reduction take place simultaneously in a given chemical reaction, it is called redox reaction or oxidation-reduction.

Answer - 1.     When oxidation and reduction take place simultaneously in a given chemical reaction, it is called redox reaction or oxidation-reduction. 2.     No oxidation can take place without reduction and there is no reduction without oxidation at the same time. 3.   When carbon monoxide is passed over heated ferric oxide, carbon monoxide gains oxygen (i.e. gets oxidized) to form carbon dioxide. At the same time, iron oxide gets reduced to metallic iron by the loss of oxygen. 4.     Fe 2 O 3  + CO → 2Fe +2CO 2  ↑

Answer - The slow process of decay or distinction ions of a metal due to the effect of air, moisture, acids, alkalies, or other chemicals on it is called corrosion.

Answer -  1.   The slow process of decay or distinction ions of a metal due to the effect of air, moisture, acids, alkalies, or other chemicals on it is called corrosion. 2.  Ordinarily, gold ornaments do not get corroded. 3.  Gold is one of the least reactive metals. It does not react with air, moisture, sweat, or ordinary pollutants in air or water. Hence, it does not get corroded.

Answer - 1.  Usually grills of doors and windows are made of iron. 2.    Iron objects get rusted on exposure to moist air. 3.  Since air always contains moisture, iron grills get rusted. 4.   Painting iron objects prevents rusting, hence iron grills of doors and windows are painted before they are used.

Answer - 1.  To make a chemical equation more informative, the physical states of the reactants and products are mentioned along with their chemical formulae. 2.   The gaseous, liquid, aqueous and solid states of reactants and products are represented by the notations (g), (l), (aq) and (s) respectively. 3.   The word aqueous (aq) is written if the reactant or product is present as a solution in water

Answer - 1.   Potassium Ferrocyanide gets decomposed when exposed to bright light. 2.   The dark colours of the bottles absorb a lot of energy from the light passing through it. 3.   If stored in dark – coloured bottles, it does not get enough light energy to decompose. 4.     Hence, potassium Ferrocyanide is stored in dark – coloured bottles and kept away from sunlight to prevent its decomposition.

Answer -  1.  One of the properties of iron is that it reacts with oxygen in the presence of moisture and gets corroded by forming rust. 2.  Air contains oxygen and moisture. Hence, iron readily rust when exposed to air. 3.   Steel (stainless steel, not mild steel) is an alloy of iron having the property to resist corrosion including rusting. 4.   Hence, stainless steel, though it contains iron, does not undergo corrosion.

Answer - 1.   If edible oil is allowed to stand for a long time in an iron or tin container the fatty acids in the oil react with rust flakes or powder to form salts. 2.  These salts contaminate the oil and hence the oil becomes rancid. 3.   Rancid oils have a foul odour and unpleasant taste. 4.   Thus, rancid oil is of no use. Hence, Edible oil is not allowed to stand for a long time in an iron or tin container to avoid rancidity.

Answer -  1.   When edible oils are left exposed to air for long period of time, they become rancid (i.e. the oils get oxidized.) 2.   Rancid oils have a foul odour and unpleasant taste. 3.   Thus, rancid oil is of no use. 4.  Edible oils is not allowed to stand exposed to air for long to avoid rancidity.

Answer - 1.     Early in the morning the air is fresh, has less pollutants due to low vehicular traffic. Breathing less polluted air gives us the feeling of freshness. 2.   After 10 a.m. vehicular traffic increases. Fast moving vehicles raise dust in the air, and the partially burnt fuels set free carbon particles and carbon monoxide. The air also gets polluted with oxides of nitrogen and sulphur dioxide (diesel, petrol contains certain amount of sulphur. 3.   Inhaling polluted air makes us feel tired.

Answer - 1.     Early in the morning the air is fresh, has less pollutants due to low vehicular traffic. Breathing less polluted air gives us the feeling of freshness. 2.   After 10 a.m. vehicular traffic increases. Fast moving vehicles raise dust in the air, and the partially burnt fuels set free carbon particles and carbon monoxide. The air also gets polluted with oxides of nitrogen and sulphur dioxide (diesel, petrol contains certain amount of sulphur. 3.   Inhaling polluted air makes us feel tired. 4.   sulphur burns in the air to produce sulphur dioxide: S + O 2  → SO 2 ↑. 5.   Partial burning of carbon (petrol, diesel, being hydrocarbon contain carbon) which produced carbon monoxide:  2C+ O2 partial burning 2CO↑ . 5. 

Answer - Rancidity is a chemical process in which edible oils or fats get oxidized over a period of time and become inedible (unfit for human consumption) is called rancidity.

Answer - The reactions in which heat is absorbed are called endothermic reactions. The reactants absorb heat for form products.

Answer - The chemical reactions in which oxidation and reduction takes place simultaneously are called redox reactions. ‘Red’ stands for reduction and ‘ox’ stands for oxidation

Answer - The chemical reaction in which an acid and alkali (base) react together to form salt and water is called neutralization. The resulting solution is neither acidic nor basic but is neutral. This reaction is known as neutralization reaction .

Answer -  1.   The atomic numbers of the elements increase as we go down the group. Thus, the elements placed lower have more electrons. 2.   To accommodate these electrons new shells are added to the atom. 3.   These new shells take the outermost electrons farther from the nucleus causing atomic size (radius) to increase as we go down the group . 3. 

Answer - An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon.  The modern meaning of "organic compound" is any one of them that contains a significant amount of carbon.  The current main definition for organic compounds doesn't fit for carbonates, simple oxides of carbon, steel, etc. So, what should be the redefined definition for organic compounds?

Answer - Now look at the below Two points for better Understanding. This is because the  s p 3 s p X 3  hybridized carbon in the alkyl group is electron donating towards the  s p 2 s p X 2 hybridized carbon in the double bond. Electron density likes to flow from low to high s-character orbitals since the more s-character in an orbital, the lower the energy of the electrons in that orbital. As the electrons flow from the  s p 3 s p X 3  carbon to the  s p 2 s p X 2  carbon the energy of the electrons (and therefore the energy of the molecule) is lowered. A "shorthand" way to illustrate this electron flow is by drawing hyperconjugated resonance structures like the following. Consequently 2-butene (where we can draw 6 hyperconjugated resonance structures) is more stable than 1-butene (where we can only draw 2 hyperconjugated resonance structures). 2) Carbanion stability decreases in the order primary > secondary > tertiary As we've just shown above, alkyl groups are el