7th Science English Medium 2nd Assignment July 2021(With Answers) Unit 2:- This is the 7th standard second assignment science English medium answer key, For Tamil medium science we shared on another page. Students must submit their assignments on time to get good marks.

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Assignment

Class: 7 Subject:SCIENCE

Unit 2
Part – A

I. One Mark Questions

1.SI unit for distance and displacement ……..

A) M

B) M²

C) K.m

D) K.m²

Answer:- A) M

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2.Speed is………

A) Distance/Time

B) Time/Distance

C) Time*Distance

D)Time+Distance

Answer:- A) Distance/Time

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3.Velocity is——

A) Displacement/hour

B) Time/Displacement

C)Dispacement/Time

D). Minutes/ Displacement

Answer:- C)Dispacement/Time

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4.SI unit of Velocity is……

A) s/m

B) m/s

C) M2/minutes

D) m/minutes

Answer:- B) m/s

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5.One girl takes 30s to complete a 300m sprint event. Find her speed?

A. 9 m/s

B. 10 m/s

C. 8 m/s

D. 7 m/s

Answer:- B. 10 m/s

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6.The rate of change in velocity is…….

A. Speed

B Time

C. Acceleration

D. M tion

Answer:- C. Acceleration

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7.Acceleration formula is …..

a) a=v-u/t

b) a=u-v/t

c) a=u-t/v

d) v=u-a/t

Answer:- a) a=v-u/t

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8.Bus at rest

A) Zero acceleration

B) Negative acceleration

C) Positive acceleration

D) Uniform acceleration

Answer:- A) Zero acceleration

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9.A particle is moving in a circular path of radius r. The displacement
after half a r circle would be……

A. Zero

B. R

C. 2r

D. r/2

Answer:- C. 2r

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10.How many types of stability?

A. 3

B. 4

C. 2.

D. 5

Answer:- A. 3

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Part – B

II. Short Answer.

1.Distinguish between speed and velocity?

Speed	Velocity
Speed is the rate of change of distance	Velocity is the rate of change in displacement
Speed = distance / time	Velocity(v) = displacement / time
Unit is metre/second (m/s)	SI unit of velocity is meter/second (m/s)

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2.What is the centre of velocity?

Any point on a rigit body or on its extension that has zero velocity is called the Instantaneous Center of Velocity of the body

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3.Mention three types of stability?

1. Stable equilibrium
2. Unstable equilibrium
3. Neutral equilibrium

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4.What is Acceleration?

1. Acceleration is the rate of change in velocity
2. Acceleration = change in velocity / time
3. SI unit of acceleration is m/s²

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5.Draw centre of gravity for regular-shaped objects?

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Part – C

III.Write in detail.

1.Explain the 3 types of stability with suitable example?

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Part – D

1.A graph is drawn between distance and time. There are two cars A
& B are with different acceleration. Which of the two is moving
faster? Justify your answer.

Car A moves faster than car B because distance covered by car A is more compared to car B and time taken by car A is less than Car B

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Unit4 ATOMIC STRATURE

Part A

I. One Mark Questions

1.Subatomic particles of atom is…….

A) 3

B) 4

C) 2

D) 5

Answer:- A) 3

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2.Who discovered the Proton

A) Ernest Rutherford

B) J.J. Thomson

C) James Chadwick

D) Daldon

Answer:- A) Ernest Rutherford

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3.Negatively charged particle is……

A) Neutron

B) Proton

C) Electron

D) Non of these

Answer:- C) Electron

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4.Atomic number of Hydrogen is……

A) 3

B) 2

C) 1

D) 5

Answer:- C) 1

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5.The proton charges is———

A) +1

B) -1

C) 0

D)+2

Answer:- A) +1

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II .Short Answer

1.What is subatomic particle?

Atoms of all elements are made up of smaller components electron,proton and neutron. These particles that make up the atom are called Subatomic particles.

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2.What are nucleons?

Protons and Neutrons are the two types of particles in the nucleus of an atom. They are called nucleons.

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3.write any four elements that are used in day today life?

• Oxygen
• Hydrogen
• Carbon
• Calcium

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III. Answer in Detail

1.Draw the atom structure and explain it