Nuisance growth of aquatic plants and bloom-forming algae in natural water is generally due to high concentrations of
carbon
sulphur
calcium
phosphorus
Algal blooms impart a distinct colour to water due to
their pigments
excretion of coloured substances
formation of coloured chemicals in water facilitated by physiological degradation of algae
absorption of light by algal cell wall
Match the items in column I and column II and choose the correct option.
| Column I | Column II | ||
|---|---|---|---|
| A. | UV | 1. | Biomagnificatron |
| B. | Biodegradable organic matter | 2. | Eutrophication |
| C. | DDT | 3. | Snow blindness |
| D. | Phosphates | 4. | BOD |
$$ \text { The correct matches is } $$
A B C D
$2 \,\quad \,1 \quad \,4 \quad\, 3$
A B C D
$3 \quad 2 \quad 4 \quad 1$
A B C D
$3 \quad 4 \quad 1 \quad 2$
A B C D
$3 \quad 1 \quad 4 \quad 2$
In the textbook you same across three mile island and chernobyl disasters associated with accidental leakage of radioactive wastes. In India we had Bhopal gas tragedy. It is associated with which of the following?
$\mathrm{CO}_2$
Methyl isocyanate
$\mathrm{CFC}^{\prime} \mathrm{s}$
Methyl cyanate
Use of lead-free petrol or diesel is recommended to reduce the pollutants emitted by automobiles. What role does lead play?
Catalytic converters, having expensive metals namely platinum, palladium and rhodium as the catalysts are fitted into automobiles for reducing emission of poisonous gases and to convert unburnt hydrocarbons into $\mathrm{CO}_2$ and $\mathrm{H}_2 \mathrm{O}$.
Motor vehicles equipped with catalytic to converter need to use unleaded petrol because lead in the petrol, inactivates the catalyst and increases the hydrocarbon emission, there by harming the environment.