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Answers
Answer:
Q2.A)
1.In the electric equipment producing heat, such as iron, electric heater, boiler, toaster etc., an alloy such as Nichrome is used, not pure metals because of the following reasons: (i) Resistivity of Nichrome is more compared to pure metal. (ii) Melting point of Nichrome is high as compared to pure metal.
2.Elements belonging to the same group have the same valency because the number of valence electrons in a group is same due to which the tendency of an atom to lose or gain electrons in order to attain nearest noble gas configuration is also same.
3.Unlike stars, planets don't twinkle. Stars are so distant that they appear as pinpoints of light in the night sky, even when viewed through a telescope. Because all the light is coming from a single point, its path is highly susceptible to atmospheric interference
B)
1.Newton's universal law of gravitation states that every particle in the universe attracts every other particle with a force along a line joining them. The force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
2.we know,
n=vc
=1.5×10^8/3×10^8=2
so the absolute refractive index of the medium is 2
3.Anomalous expansion of water refers to water's unusual ability, due to which it expands instead of contracting when cooled. Due to some reasons like rains or a flowing river, water enters the rocks through small spaces in between them. In winters, in areas with extremely low temperatures, this water expands due to its abilities and thus causes the rocks to crack.
4.The phenomenon of splitting of light into its component colours is called dispersion of light. When white light passes through a glass prism, it spreads out into a band of different colours called the spectrum of light. The colours in the spectrum of white light are violet, indigo, blue, green, yellow, orange and red.
5.Dobereiner stated in his law of triads that the arithmetic mean of the atomic masses of the first and third element in a triad would be approximately equal to the atomic mass of the second element in that triad.