Problem 36
Organic matter is considered as a major source of water pollution caused by wastes of food, animal and human excreta, garbage etc. The excess of organic matter in water causes a threat to aquatic life because (a) the space available to aquatic life decreases (b) microorganisms consume dissolved oxygen to decompose organic matter (c) organic matter is swallowed by small animals (d) decomposition of organic matter increases the temperature of water.
Problem 39
Biological Oxygen Demand (BOD) can be defined as, (a) the amount of oxygen required by bacteria to break down the organic matter of a sample of water (b) the amount of chemicals required to break (c) the amount of phosphate required to oxidise the organic matter of a sample of water (d) the amount of organic matter present in the given sample of water.
Problem 44
As DDT passes into food chain, its concentration (a) remains same (b) decreases (c) becomes zero (d) increases.
Problem 45
Match the column 1 with column II and mark the appropriate choice. $$ \begin{array}{|l|l|l|l|} \hline \text { (A) } & \begin{array}{l} \text { Toxic heavy } \\ \text { metals } \end{array} & \text { (i) } & \text { Domestic sewage } \\ \hline \text { (B) } & \text { Microorganisms } & \text { (ii) } & \begin{array}{l} \text { Industries and } \\ \text { chemical factories } \end{array} \\ \hline \text { (C) } & \text { Organic wastes } & \text { (iii) } & \text { Chemical fertilizers } \\ \hline \text { (D) } & \text { Plant nutrients } & \text { (iv) } & \begin{array}{l} \text { Discharge from food } \\ \text { processing factories } \end{array} \\ \hline \end{array} $$ (a) \((A) \rightarrow(\) i \(),(B) \rightarrow\) (iii), (C) \(\rightarrow\) (ii), (D) \(\rightarrow\) (iv) (b) (A) \(\rightarrow\) (iii), (B) \(\rightarrow\) (iv), (C) \(\rightarrow\) (i), (D) \(\rightarrow\) (ii) (c) (A) \(\rightarrow\) (iv), (B) \(\rightarrow\) (ii), (C) \(\rightarrow\) (iii), (D) \(\rightarrow\) (i) (d) (A) \(\rightarrow\) (ii), (B) \(\rightarrow\) (i), (C) \(\rightarrow\) (iv), (D) \(\rightarrow\) (iii)
Problem 47
Match the column I with column II and mark the appropriate choice. $$ \begin{array}{|l|l|l|l|} \hline \text { (A) } & \begin{array}{l} \text { Biodegradable } \\ \text { pollutants } \end{array} & \text { (i) } & \text { DDT } \\ \hline \text { (B) } & \begin{array}{l} \text { Non-biodegradable } \\ \text { pollutants } \end{array} & \text { (ii) } & \mathrm{SO}_{2} \\ \hline \text { (C) } & \text { Primary pollutants } & \text { (iii) } & \text { PAN } \\ \hline \text { (D) } & \text { Secondary pollutants } & \text { (iv) } & \text { Sewage } \\ \hline \end{array} $$ (a) \((\mathrm{A}) \rightarrow\) (iii), (B) \(\rightarrow\) (iv), (C) \(\rightarrow\) (ii), (D) \(\rightarrow\) (i) (b) \((\mathrm{A}) \rightarrow(\mathrm{ii}),(\mathrm{B}) \rightarrow(\mathrm{iii}),(\mathrm{C}) \rightarrow(\mathrm{iv}),(\mathrm{D}) \rightarrow\) (i) (c) \((\mathrm{A}) \rightarrow(\mathrm{i}),(\mathrm{B}) \rightarrow(\mathrm{ii}),(\mathrm{C}) \rightarrow(\mathrm{iii}),(\mathrm{D}) \rightarrow(\mathrm{iv})\) (d) \((\mathrm{A}) \rightarrow(\mathrm{iv}),(\mathrm{B}) \rightarrow(\mathrm{i}),(\mathrm{C}) \rightarrow(\mathrm{ii}),(\mathrm{D}) \rightarrow(\mathrm{iii})\)
Problem 48
Which of the tollowing practices involve green chemistry? (i) Substitute CFCs by environmental friendly HFCs and other compounds. (ii) Replace halogenated solvent by liquid \(\mathrm{CO}_{2}\) for drycleaning. (iii) Use of \(\mathrm{H}_{2} \mathrm{O}_{2}\) for bleaching instead of \(\mathrm{Cl}_{2}\). (iv) Making disposable eating utensils and storage jars of plastics. (a) (i) and (ii) (b) (ii) and (iv) (c) (iii) and (iv) (d) (i), (ii) and (iii)
Problem 49
Green chemistry involves (a) production of chemicals of our daily use from green house gases (b) such chemical processes in which green plant are used (c) those reactions which are of biological origin (d) use of non-toxic reagents and solvents to produce environment friendly products.
Problem 50
Which of the following practices will come under green chemistry? (a) If possible, making use of soap made of vegetable oils instead of using synthetic detergents (b) Using \(\mathrm{H}_{2} \mathrm{O}_{2}\) for bleaching purpose instead of using chlorine based bleaching agents (c) Using bicycle for travelling small distances instead of using petrol/diesel based vehides (d) All of these.
