if you are looking for Tamil Nadu Board Class 7 Science Chapter 1 Measurements then you are at the right place.
[I] Choose the best answer.
Which of the following is a derived quantity?
- a) mass
- b) time
- c) area
- d) length
Which of the following is correct?
- a) 1L = 1cc
- b) 1L = 10 cc
- c) 1L = 100 cc
- d) 1L = 1000 cc
SI unit of density is………..
- a) kg/m2
- b) kg/m3
- c) kg/m
- d) g/m3
Two spheres have mass and volume in the ratio 2:1. The ratio of their density is………
- a) 1:2
- b) 2:1
- c) 4:1
- d) 1:4
Light year is the unit of……….
- a) distance
- b) time
- c) density
- d) Both length and time
[II] Fill in the blanks.
- Volume of irregularly shaped objects are measured using the law of ______________.[Archimedes]
- One cubic metre is equal to _____________ cubic centimetre.[1,000,000]
- Density of mercury is _______________.[13,600 kg/m3]
- One astronomical unit is equal to _______.[149.6 million kilometers]
- The area of a leaf can be measured using a ________________________.[graph sheet or by approximation]
[III] State true or false. If false, correct the statement.
- The region covered by the boundary of a plane figure is called its volume.[False -Correction: The region covered by the boundary of a plane figure is called its area, not volume.]
- Volume of liquids can be found using measuring containers.[True]
- Water is denser than kerosene.{true]
- A ball of iron floats in mercury.[False – A ball of iron sinks in mercury]
- A substance which contains less number of molecules per unit volume is said to be denser.[False. Correction: A substance which contains more number of molecules per unit volume is said to be denser.]
[V] Arrange the following in correct sequence.
- 1L, 100 cc, 10 L, 10 cc
10 cc, 100 cc, 1L, 10 L
- Copper, Aluminium, Gold, Iron
Aluminium, Copper, Iron, Gold
[VI] Use the analogy to fill in the blank
- Area : m2 :: Volume : _________[m^3]
- Liquid : Litre :: Solid : _________[Cubic meter (m^3)]
- Water : Kerosene :: _______ : Aluminium [copper]
[VII] Consider the following statements and choose the correct option.
- Assertion: Volume of a stone is found using a measuring cylinder. –Reason: Stone is an irregularly shaped object.
False. The assertion is incorrect because while stones are irregularly shaped, their volume is typically measured using displacement method rather than a measuring cylinder.
- Assertion: Wood floats in water. –Reason: Water is a transparent liquid.
False. The assertion is incorrect. Wood floats in water not because water is transparent, but because wood is less dense than water, allowing it to float.
- Assertion: Iron ball sinks in water. Reason: Water is denser than iron.
- Both assertion and reason are true and reason is the correct explanation of assertion.
- Both assertion and reason are true, but reason is not the correct explanation of assertion.
- Assertion is true but reason is false.
- Assertion is false but reason is true.
Both assertion and reason are true, but reason is not the correct explanation of assertion.
While it’s true that an iron ball sinks in water and water is denser than iron, the reason provided is not the correct explanation. The sinking of the iron ball is due to its higher density compared to water, which causes it to displace water and sink.
[VIII] Answer very briefly.
Name some of the derived quantities.
Some derived quantities include area, volume, density, speed, and acceleration.
Give the value of one light year.
One light year is approximately equal to 9.46 trillion kilometers, representing the distance light travels in vacuum over the span of one year.
Write down the formula used to find the volume of a cylinder.
The formula to find the volume of a cylinder is V = πr^2h, where V represents volume, r is the radius, and h is the height of the cylinder.
Give the formula to find the density of objects.
The formula to find the density of objects is Density (D) = Mass (M) / Volume (V).
Name the liquid in which iron ball sinks.
The liquid in which an iron ball sinks is water, due to water’s higher density compared to iron.
Name the units used to measure the distance between celestial objects.
The units used to measure the distance between celestial objects include astronomical units (AU) and light years (ly).
What is the density of gold?
The density of gold is approximately 19,320 kilograms per cubic meter (kg/m^3).
[IX] Answer briefly.
What are derived quantities?
Derived quantities are physical quantities obtained by combining fundamental quantities mathematically. Examples include area, volume, and density.
Distinguish between the volume of liquid and capacity of a container.
The volume of a liquid refers to the amount of space it occupies, while the capacity of a container is the maximum volume of liquid or substance it can hold.
Define the density of objects.
Density of objects is the mass of a substance per unit volume. It indicates how much mass is packed into a given volume and is often expressed in kilograms per cubic meter (kg/m³).
What is one light year?
One light year is the distance that light travels in vacuum over the span of one year. It is approximately equal to 9.46 trillion kilometers.
Define – Astronomical unit.
An astronomical unit (AU) is the average distance between the Earth and the Sun, which is approximately 149.6 million kilometers. It’s used as a unit of measurement in astronomy to express distances within the solar system.
[X] Answer in detail
Describe the graphical method to find the area of an irregularly shaped plane figure.
Do it on your own
How will you determine the density of a stone using a measuring jar?
To determine the density of a stone using a measuring jar, you can follow the displacement method. First, fill the measuring jar with a known volume of water and record the initial volume reading. Then, carefully lower the stone into the water, ensuring it is fully submerged. Measure and record the new volume reading, which will be greater than the initial volume due to the displacement of water by the stone. The difference between the final and initial volume readings represents the volume of water displaced by the stone. Since density equals mass divided by volume, you can calculate the density of the stone by dividing its mass by the volume of water displaced.
[XII] Numerical problems:
A circular disc has a radius 10 cm. Find the area of the disc in m2 (Use π = 3.14).
- Area of the circular disc =π×radius2=π×radius2
- Given: radius (rr) = 10 cm
- Area =3.14×102=3.14×102 =314 cm2=314 cm2
- Converting to square meters: 314 cm2314 cm2 =0.0314 m2=0.0314 m2
The dimension of a school playground is 800 m × 500 m. Find the area of the ground.
- Area of the school playground =length×width=length×width
- Given: Length = 800 m, Width = 500 m
- Area =800×500=800×500 =400,000 m2=400,000 m2
Two spheres of same size are made from copper and iron respectively. Find the ratio between their masses (Density of copper is 8,900 kg/m3 and iron is 7,800 kg/m3).
- Ratio of masses of spheres made from copper and iron respectively:
- Given: Density of copper (DcopperDcopper) = 8,900 kg/m³, Density of iron (DironDiron) = 7,800 kg/m³
- As the size of the spheres is the same, the ratio of their masses will be the same as the ratio of their densities.
- Ratio of masses =DcopperDiron=8900/7800=89/78
A liquid having a mass of 250 g fills a space of 1000 cc. Find the density of the liquid.
- Density of the liquid =MassVolume=VolumeMass
- Given: Mass = 250 g, Volume = 1000 cc
- Density =250 g1000 cc=1000 cc250 g =0.25 g/cc=0.25 g/cc
A sphere of radius 1cm is made from silver. If the mass of the sphere is 33g, find the density of silver (Take π = 3.14).
- Density of silver =MassVolume=VolumeMass
- Given: Mass = 33 g, Radius = 1 cm
- Volume of sphere =43πr3=34πr3
- =43×3.14×(1)3=34×3.14×(1)3 =4.186 cm3=4.186 cm3
- Density =33 g4.186 cm3=4.186 cm333 g =7.88 g/cm3=7.88 g/cm3
