Science 2005 CBSE [ All India ] Set III
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Q1
Write the chemical equation to represent the reaction taking place when copper oxide is heated in a stream of hydrogen. Marks:1View AnswerAnswer:
CuO + H2
Cu + H2O -
Q2
Name two metals both of which are very ductile as well as very malleable. Marks:1View AnswerAnswer:
Silver and Gold. -
Q3
A wire of resistance 10 ohm is bent in the form of a closed circle. What is the effective resistance between the two points at the ends of any diameter of the circle? Marks:1View AnswerAnswer:
Effective resistance (R) between the two points at the end of the diameter of the circle is a combination of two 5 ohm resistances.
1/R = 1/5 +1/51/R = 2/5 R = 2.5 ohm -
Q4
What is the function of genes in an organism? Marks:1View AnswerAnswer:
Genes are the segments of DNA which control the traits and characteristics of an individual. -
Q5
Why is it necessary to conserve our environment? Marks:1View AnswerAnswer:
We are the part of our environment and fulfill our needs through the environment. Any kind of harm will finally affect us hence we need to conserve our environment. -
Q6
What is observed when a mixture of hydrogen and chlorine is exposed to sunlight? What is the product formed? Marks:1View AnswerAnswer:
Hydrogen reacts with chlorine in the presenec of sunlight to form hydrogen chloride.
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Q7
A wire of resistance 20 ohm is bent in the form of a closed circle. What is the effective resistance between the two points at the ends of any diameter of the circle? Marks:1View AnswerAnswer:
Effective resistance (R) between the two points at the end diameter of the circle is a combination of two 10 ohm resistances. 1/R = 1/10 +1/10 1/R = 2/10 R = 5 ohm -
Q8
What is a genetically modified organism (GMO)? Marks:1View AnswerAnswer:
Out of syllabus. -
Q9
Light enters from air into a glass plate which has a refractive index of 1.50. Calculate the speed of light in glass. The speed of light in air is 3.0 x 108 ms-1. Marks:2View AnswerAnswer:
Speed of light in air = 3.0 x 108 ms-1
Let, speed of light in glass = v
Refractive index of glass (n) = 1.50
n = speed of light in air/speed of light in glass
1.50 = (3.0 x 108) / v
Or,v = (3.0 x 108) / 1.50
Or,v = 2.0 x 108 ms-1 -
Q10
What happens when crystals of washing soda are left open in dry air? What is this change named as? Name two industries based on use of washing soda. Marks:2View AnswerAnswer:
When crystals of washing soda are left open in air, the crystals lose 9 of their water molecules. Second part of the question is out of syllabus. Two industries based on washing soda are glass and soap industries.
