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प्रश्न
Write true or false.
Every measurement involves two things – a number and a unit.
विकल्प
True
False
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उत्तर
True
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संबंधित प्रश्न
The nearest star to our solar system is 4.29 light years away. How much is this distance in terms of parsecs? How much parallax would this star (named Alpha Centauri) show when viewed from two locations of the Earth six months apart in its orbit around the Sun?
Match the following.
| 1. | Length | kelvin |
| 2. | Mass | metre |
| 3. | Time | kilogram |
| 4. | Temperature | second |
Assertion (A): Distance between two celestial bodies is measured in terms of light year.
Reason (R): The distance travelled by the light in one year is one light year.
Guess whose tail is the longest. Now measure the tails. How good is your guess?
The fencing of a square garden is 20 m in length. How long is one side of the garden?
So Anar also tried many different ways to make a boundary for 800 square meters of land.
He made rectangles A, B, and C of different sizes. Find out the length of the boundary of each. How much gold wire will he get for these rectangles?
- A
Gold wire for A = _________ metres - B
Gold wire for B = _________ metres - C
Gold wire for C = __________ metres
But then Anar made an even longer rectangle... See how long!
- D
So he will get __________ metres of gold wire!!
There are two beautiful lakes near a village. People come for boating and picnics in both the lakes. The village Panchayat is worried that with the noise of the boats the birds will stop coming. The Panchayat wants motorboats in only one lake. The other lake will be saved for the birds to make their nests.
- How many kilometers long is the actual boundary of lake A?
The radius of atom is of the order of 1 Å and the radius of nucleus is of the order of fermi. How many magnitudes higher is the volume of atom as compared to the volume of nucleus?
In an experiment to estimate the size of a molecule of oleic acid 1 mL of oleic acid is dissolved in 19 mL of alcohol. Then 1 mL of this solution is diluted to 20 mL by adding alcohol. Now 1 drop of this diluted solution is placed on water in a shallow trough. The solution spreads over the surface of water forming one molecule thick layer. Now, lycopodium powder is sprinkled evenly over the film and its diameter is measured. Knowing the volume of the drop and area of the film we can calculate the thickness of the film which will give us the size of oleic acid molecule.
Read the passage carefully and answer the following questions:
- Why do we dissolve oleic acid in alcohol?
- What is the role of lycopodium powder?
- What would be the volume of oleic acid in each mL of solution prepared?
- How will you calculate the volume of n drops of this solution of oleic acid?
- What will be the volume of oleic acid in one drop of this solution?
How many astronomical units (A.U.) make 1 parsec?
