A person was using water supplied by the Municipality.
Question: A person was using water supplied by the Municipality. Due to the shortage of water, he started using underground water. He felt a laxative effect. What could be the cause? Solution: The laxative effect is the effect caused by laxative substances that loosen stools and increases bowel movement. High doses of laxatives may even cause diarrhoea. This can be due to the excessive presence of sulphate in drinking water....
Read More →Some time ago the formation of polar stratospheric clouds
Question: Some time ago the formation of polar stratospheric clouds was reported over Antarctica. Why were these formed? What happens when such clouds break up by the warmth of sunlight? Solution: This is depletion of the ozone layer. In the summer season, the nitrogen dioxide and methane reacted with the chlorine monoxide and chlorine radicle respectively forming chlorine sinks thereby preventing the depletion of ozone. ClO + NO2 (g) ClONO2 Cl (g) + CH4 CH3(g) + HCl (g) ClONO2 (g) +H2O HOCl (g)...
Read More →Ozone is a gas heavier than air.
Question: Ozone is a gas heavier than air. Why does the ozone layer not settle down near the earth? Solution: The ozone layer is heavier than oxygen and is thermodynamically unstable and there is a dynamic equilibrium in the reaction between formation and dissociation of the ozone. So they do not settle down near the earth. O2 (g) O (g) + O (g) O (g) + O2 (g) O3 (g)...
Read More →How is ozone produced in stratosphere?
Question: How is ozone produced in stratosphere? Solution: The ozone layer is formed in the stratosphere by the action of U. V radiations on the atmospheric oxygen. UV radiations cause the splitting or dissociation of molecular oxygen to two oxygen atoms O 2 (g) O (g) + O (g) Now the oxygen atom combines with other molecular oxygen to form Ozone O (g) + O2 (g) O3 (g)...
Read More →From where does ozone come
Question: From where does ozone come in the photochemical smog? Solution: The composition of photochemical smog is nitrogen oxides, Volatile organic compounds (VOC), ozone, PAN i.e. peroxyacetyl nitrate. nitrogen oxide present in the smog undergoes dissociation in the presence of sunlight to NO and nascent oxygen (O) NO2 (g) NO (g) + O (g) The nascent oxygen reacts with oxygen gas to form ozone gas along with inert gas. O (g) + O2 (g) + M O3 (g) + M(inert gas)...
Read More →Oxidation of Sulphur dioxide into Sulphur trioxide
Question: Oxidation of Sulphur dioxide into Sulphur trioxide in the absence of a catalyst is a slow process but this oxidation occurs easily in the atmosphere. Explain how does this happen. Give chemical reactions for the conversion of SO2 into SO3. Solution: Oxidation of sulphur dioxide to sulphur trioxide is slow in uncatalysed reaction but easily can be oxidized in the presence of a catalyst in the atmosphere. The atmosphere contains matters which can act as a catalyst. 2SO2 (g) + O2 (g) 2SO3...
Read More →A factory was started near a village.
Question: A factory was started near a village. Suddenly villagers started feeling the presence of irritating vapours in the village and cases of headache, chest pain, cough, dryness of throat and breathing problems increased. Villagers blamed the emissions from the chimney of the factory for such problems. Explain what could have happened. Give chemical reactions for the support of your explanation. Solution: The harmful oxides of nitrogen and sulphur in the atmosphere can cause this type of br...
Read More →Why does water cover with excessive
Question: Why does water cover with excessive algal growth become polluted? Solution: The decomposition of algae by the bacteria continuously produces foul smell and the algae make water polluted and undesirable. The amount of dissolved oxygen also decreases and can lead to the death of aquatic animals...
Read More →What is the importance of measuring
Question: What is the importance of measuring BOD of a water body? Solution: Biochemical oxygen demand (BOD) is defined as the amount of oxygen required by the bacteria to decompose the organic matter. Higher the BOD of water highly polluted is the water. Lesser the BOD of waterless polluted is the water. Drinking water has BOD of the range of less than 5ppm and highly polluted water have BO D of the value of 17ppm or more....
Read More →Reduce the equation
Question: Reduce the equation $x+\sqrt{3} y-4=0$ to the normal form x cos + y sin = p, and hence find the values of and p Solution: Given equation is $x+\sqrt{3} y-4=0$ If the equation is in the form of ax + by = c, to get into the normal form, we should divide it by $\sqrt{a^{2}+b^{2}}$ so now Divide by $\sqrt{\sqrt{3}^{2}+1^{2}}=2$ Now we get $\Rightarrow \frac{x}{2}+\frac{\sqrt{3} y}{2}=1$ This is in the form of $x \cos \alpha+y \sin \alpha=p$ Where $\cos \alpha=\frac{1}{2} \Rightarrow \alpha...
Read More →What are the sources of dissolved
Question: What are the sources of dissolved oxygen in water? Solution: Oxygen reaches the water through the atmosphere where there is direct contact of water with atmospheric air. Photosynthesis by green aquatic plants at day time. In the night the photosynthesis does not take place but the plants respire but the amount of oxygen is reduced....
Read More →What are biodegradable and
Question: What are biodegradable and non-biodegradable pollutants? Solution: Biodegradable pollutants are those which can be decomposed by bacteria or any other environmental factors like fruits, sewages etc. Non-biodegradable pollutants are not easily decomposed by bacteria. It remains as such in the environment. Examples like DDT, mercury etc....
Read More →Find the intervals in which the following functions are increasing or decreasing.
Question: Find the intervals in which the following functions are increasing or decreasing. $f(x)=3 x^{4}-4 x^{3}-12 x^{2}+5$ Solution: Given:- Function $f(x)=3 x^{4}-4 x^{3}-12 x^{2}+5$ Theorem:- Let $f$ be a differentiable real function defined on an open interval $(a, b)$. (i) If $f^{\prime}(x)0$ for all $x \in(a, b)$, then $f(x)$ is increasing on $(a, b)$ (ii) If $f^{\prime}(x)0$ for all $x \in(a, b)$, then $f(x)$ is decreasing on $(a, b)$ Algorithm:- (i) Obtain the function and put it equal...
Read More →During an educational trip,
Question: During an educational trip, a student of botany saw a beautiful lake in a village. She collected many plants from that area. She noticed that villagers were washing clothes around the lake and at some places waste material from houses was destroying its beauty. After a few years, she visited the same lake again. She was surprised to find that the lake was covered with algae, the stinking smell was coming out and its water had become unusable. Can you explain the reason for this conditi...
Read More →What could be the harmful effects
Question: What could be the harmful effects of improper management of industrial and domestic solid waste in a city? Solution: The improper management of industrial and domestic waste in a city can cause serious damages to both living and non-living things. 1. Domestic waste if not disposed of properly it will lead to the blockage of sewage lines and thus mosquitoes will grow in the water and cause dengue-like diseases. 2. Improper management of such domestic wastes contributes to soil pollution...
Read More →Based on chemical reactions involved,
Question: Based on chemical reactions involved, explain how chlorofluorocarbons cause thinning of the ozone layer in the stratosphere. Solution: The action of U.V rays causes the dissociation of chlorofluorocarbons to release the free chlorine radicle CF2Cl2 + U V radiations Cl + CFC Now this Chlorine radicle so formed is free and in the stratospheric layer reacts with the Ozone to form Chlorine monoxide and oxygen Cl (g) +O3 (g) ClO (g)+O2(g) chlorine monoxide reacts with the nascent oxygen and...
Read More →Dissolved oxygen in water is very important
Question: Dissolved oxygen in water is very important for aquatic life. What processes are responsible for the reduction of dissolved oxygen in water? Solution: Eutrophication is the process responsible for the reduction of dissolved oxygen in the water. It is a process in which nutrient-enriched water bodies support a dense plant population, which kill animal life by depriving of oxygen and result in subsequent loss of biodiversity....
Read More →Ozone is a toxic gas and is a strong oxidizing
Question: Ozone is a toxic gas and is a strong oxidizing agent even then its presence in the stratosphere is very important. Explain what would happen if ozone from this region is completely removed? Solution: If ozone is removed the ultraviolet radiation comes directly in contact with living things and cause damages such as skin cancers and many other serious diseases. Ozone in the stratosphere absorbs this UV radiation from the sun and does not allow to pass it to the inner atmosphere....
Read More →Reduce the equation
Question: Reduce the equation $x+\sqrt{3} y-4=0$ to the normal form $x \cos \alpha+y \sin \alpha=$ $p$, and hence find the values of $\propto$ and $p$. Solution: Given equation is $x+\sqrt{3} y-4=0$ If the equation is in the form of ax + by = c, to get into the normal form, we should divide it by $\sqrt{a^{2}+b^{2}}$ so now Divide by $\sqrt{\sqrt{3}^{2}+1^{2}}=2$ Now we get $\Rightarrow \frac{\mathrm{x}}{2}+\frac{\sqrt{3} \mathrm{y}}{2}=1$ This is in the form of $x \cos \alpha+y \sin \alpha=p$...
Read More →Acid rain is known to contain some
Question: Acid rain is known to contain some acids. Name these acids and where from they come in the rain? Solution: Acid rain is the result of human activities that emit the oxides of sulphur and nitrogen in the atmosphere. 2SO2 (g) + O2 (g) + 2H2O (l) 2H2SO4 (aq) 4NO2 (g) + O2 (g)+ 2H2O (l) 4HNO3 (aq) . Nitric acid and sulphuric acid are acids present in acid rain which causes harmful effects to both living and non-living things....
Read More →Greenhouse effect leads to global warming.
Question: Greenhouse effect leads to global warming. Which substances are responsible for the greenhouse effect? Solution: Gases such as carbon dioxide, methane, ozone, chlorofluorocarbon compounds (CFCs) and water vapour which are all greenhouse gases that are responsible for the greenhouse effect leading to global warming....
Read More →The consequences of global warming
Question: The consequences of global warming may be _________. (i) increase in average temperature of the earth (ii) melting of Himalayan Glaciers. (iii) increased biochemical oxygen demand. (iv) eutrophication. Solution: Option (i) and (ii) are the answers....
Read More →Find the intervals in which the following functions are increasing or decreasing.
Question: Find the intervals in which the following functions are increasing or decreasing. $f(x)=\{x(x-2)\}^{2}$ Solution: Given:- Function $f(x)=\{x(x-2)\}^{2}$ Theorem:- Let $f$ be a differentiable real function defined on an open interval $(a, b)$. (i) If $f^{\prime}(x)0$ for all $x \in(a, b)$, then $f(x)$ is increasing on $(a, b)$ (ii) If $f^{\prime}(x)0$ for all $x \in(a, b)$, then $f(x)$ is decreasing on $(a, b)$ Algorithm:- (i) Obtain the function and put it equal to $f(x)$ (ii) Find $f^...
Read More →The acids present in acid rain are _________.
Question: The acids present in acid rain are _________. (i) Peroxyacetylnitrate (ii) H2CO3 (iii) HNO3 (iv) H2SO4 Solution: Option (ii), (iii) and (iv) are the answers....
Read More →Phosphate containing fertilisers
Question: Phosphate containing fertilisers cause water pollution. Addition of such compounds in water bodies causes __________. (i) enhanced growth of algae. (ii) the decrease in the amount of dissolved oxygen in the water. (iii) deposition of calcium phosphate. (iv) increase in the fish population. Solution: Option (i) and (ii) are the answers....
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