Short Answer TypeList the products of combustion of fossil fuels. What are their adverse effects on the environment?
Fossil fuels like coal contain carbon, hydrogen, nitrogen and sulphur. When these are burnt, the products are carbon dioxide, water, oxides of nitrogen and oxides of sulphur. When burnt in an insufficient atmosphere (less oxygen), then carbon monoxide is formed instead of carbon dioxide. Of these products, the oxides of sulphur and nitrogen and carbon monoxide are poisonous at high concentrations and cause air pollution. The carbon dioxide is a greenhouse gas which results in global warming.
List three problems which arise due to the construction of big dams. Suggest a solution for these problems.
State the meaning of inherited traits and acquired traits. Which of the two is not passed on to the next generation? Explain with the help of an example.
How are fossils formed? Describe, in brief, two method of determining the age of fossils.
If pure-bred tall (dominant) pea plant is crossed with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we cross the pea plant of F1 generation then we obtain pea plants of F2 generation.
(a) What do the plants of the F2 generation look like?
(b) State the ratio of tall plants to dwarf plants in F2 generation
(c) State the type of plants not found in F1 generation but appeared in F2 generation, mentioning the reason for the same.
Long Answer TypeWhat is hydrocarbon? Write the name and general formula of (i) saturated hydrocarbon, (ii) unsaturated hydrocarbon, and draw the structure of one hydrocarbon of each type.How can unsaturated hydrocarbon be made saturated?
What are detergents chemically? List two merits and two demerits of using detergent for cleaning. State the reason for the suitability of detergents for washing,event in the case of water having calcium and magnesium ions.
With the help of a ray diagram, state what is meant by refraction of light. State Snell’s law for refraction of light and also express it mathematically.
The refractive index of air with respect to glass is 2/3 and the refractive index of water with respect to air is 4/3. If the speed of light in glass is 2 x 108 m/s, find the speed of light in:
a) air, b) water.
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