Science 2005 CBSE [ Delhi ] Set III
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Q1
Name a metal which offers higher resistance to the passage of electricity than copper. Marks:1View AnswerAnswer:
Iron -
Q2
State a reaction in which SO2 acts as an oxidising agent. Out of syllabus. Marks:1View AnswerAnswer:
Out of syllabus. -
Q3
Which has a higher resistance: a 50 W lamp bulb or a 25 W lamp bulb and how many times? Marks:1View AnswerAnswer:
A 25 W lamp bulb has a higher resistance and it will be twice than that of the 50 W lamp bulb. -
Q4
Why is one arm in sub-metacentric chromosome longer than the other? Marks:1View AnswerAnswer:
Out of syllabus. -
Q5
What is 'Green House Effect'? Marks:1View AnswerAnswer:
The phenomenon of trapping of reflected infrared sunrays by gases like carbon dioxide in the atmosphere is called as Green-house effect. -
Q6
A green layer is gradually formed on a copper plate left exposed to air for a week in a bathroom. What could this green substance be? Marks:1View AnswerAnswer:
Copper carbonate. -
Q7
Why is tungsten metal selected for making filaments of incandescent lamp bulbs? Marks:1View AnswerAnswer:
Tungsten is used for making filaments of incandescent lamp bulbs because it has high melting point and does not melt even at the high temperature. -
Q8
How are metacentric and acrocentric chromosomes different from each other in shape? Marks:1View AnswerAnswer:
Out of syllabus. -
Q9
Describe any one technique of controlling gaseous pollutants of air. Marks:2View AnswerAnswer:
Out of syllabus. -
Q10
How is plaster of Paris chemically different from gypsum? How may they be interconverted? Write one use of plaster of Paris. Marks:2View AnswerAnswer:
Plaster of Paris is calcium sulphate hemihydrate whereas gypsum is calcium sulphate dihydrate. Plaster of Paris can be converted to gypsum by mixing it with water. Gypsum can be converted to plaster of Paris by heating gypsum at 373 K. Plaster of Paris is used to make toys and decorative materials.
