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Answers.Sc.

posted Nov 19, 2015, 12:32 AM by Upali Salpadoru   [ updated Aug 9, 2019, 4:50 PM ]
 
A
Atoms and Molecules.

Q.1.0

    1. Atom.  2. Electron.  3. Molecule 4. Proton.5 . Cation. 6. Molecule.

 


Q.2.0

2.1

Atomic no.

Atomic Mass

Protons

Electrons

Neutrons

X  H

1

2

1

1

1

Y  C

6

14

6

6

8

Z  O

8

16

8

8

8

9 Marks


2.2    X.     2.3   Z,    

2.4    X4Y    or   YX4


Q 3.0     .     

                     

Q. No

Formula

Bond type

1

HF

Ionic or Covalent.

 2

MgCl2.

Ionic

 3

B2O3

Covalent. (2 non metals)

 4

SiF4

Covalent

 5.

P2O5

Covalent


 Q 4.0


Chlorides

Cl-

Hydroxides

OH-

Carbonate

CO32-

Nitrate

NO3-

Hydrogen   H+

HCl

HOH

H2CO3

HNO3

Sodium

Na+

NaCl

NaOH

Na2CO3

NaNO3

Calcium

Ca++

CaCl2

Ca(OH)2

CaCO3

CaNO3

Aluminium

Al +++

AlCl3

Al(OH)3

Al2(CO3)3

Al (NO3)3

Ammonium

NH4 +

NH4Cl

NH4OH

(NH4)2 CO3

NH4NO3

Silver Ag +

AgCl

AgOH

Ag2CO3

AgNO3


Marks 20.


B
C
D
E

Electroscope.


Part A    Multiple choice Questions

  1. A, 2. B  3. C 4.D  5. D  6. D 7. A  8. A

           
1. Negative  
2  Movement of electrons (negative charge)

                   3.   Repulsion due to negative charge on both foils.

                   4.  Electroscope will get a negative charge.

                  5.  Remain extended.


2.0

  1. a.  Foil moves up.  b.  The plate will push the electrons to the foil.

  2. a. Foil will remain divulged   b. The foil and rod will have the same positive charge.

  3. a. Foil goes down   b. Electrons repelling from plate will neutralize the foil and rod.

2.4    a.  Foil comes down.         b. Extra electrons go to earth.
2.5    a.  Foil repels. 
                           b. As some electrons have gone to earth electroscope will have a positive           charge.
3.0
Hang the two balloons with thread

Rub the glass rod with the piece of silk. ( This will give a positive charge to the glass)

Bring the glass rod near the balloons .

One that attracts will be negative and the one that repels will be positive.



4.0  
1.A- conductor,  B-Insulator,  C-Insulator  D- Conductor   E- Conductor.  
2. Electrons.         3. Positive        
4.  Hold one end of a copper wire at A and bring the other end to E.    
5.  Electrons can come from earth to E.

F





Forces- Friction


1.11. Weight, 2. Friction 3 Support  4. Pull.

1.2  1 and 3 are equal.

1.3  b. 3N.

1.4  c. 4N.

Q. 2.0

2.1 Mud guard and spokes.

2.2 Gear wheels, Chain, axle.

2.3 Axle.

2.4 Tyre and brake shoes.

2.5 To increase friction. 1. Helps traction. 2. Prevent skidding on bends.

3.0  3.1  c. ,   3.2. a.   3.3  i. using a lubricant, adding wheels,  ii. Tighten the grip, use a rope of high friction, use gloves of high friction or wrap the rope round the arm. iii.  Use rubber, treads or spikes,

4.0  4.1 c.,  4.2. b.,  4.3  b.

5.0


G

H

  Heat - Hot and Cold.

1.0

Flask.jpg

2.0    1. Radiation,  2. Conduction,   3.  Convection,  4.  Radiation.

3.0  

Good conductors

Poor conductors.

Non conductors Insulators

Copper

Iron

Aluminium

lead

Brass


glass

Stones (granite)

Concrete

ceramics

pyrex

water

wool

wood

rubber

plastic


4.0  

  1. Conduction through glass.

  2. Heat and may even boil.   ice will not melt.

  3. Water and glass are bad (poor) conductors.

  4. Mercury.

5.0

1

2

3

4

5

6

7

8

9

10

B

A

C

D

B

D

D

A

C

A (B)


Q 6.0

6.1

Th.jpg

6.2                                               

  1. Mercury is a good conductor of heat.


b   Alcohol has a freezing point lower than that of mercury.

6.3   B.





I

J

K

L

  • Levers.

Q.1.0

  1. CW Moments = 400x2.5

  2. ACW moments = Lx 2

  3. 2L = 1000

          L = 500 N

   4.  Reaction at P =  900 N up.


Q.2.0 A

  1. CW= 2x400 = 800 Nm

  2. ACW =1x600= 600 Nm.

  3. Rotate clockwise.

  4. Then ACW = 1.5x600 = 900Nm.

  5. Rotate anticlockwise.

Q. 3.0

  1. 25x40 .N cm.

  2. 5 x E  Ncm.

  3. 5E = 1000

          E = 200 N.

   4.   Higher.          5.  No.

Q.4.0

  1.     CW moments = (3x560) + 1x 320  = 2000Nm.

  2. ACW moments =  5 x A

  3.  5A =  2000  ,  Therefore A =  400 N.

  4. Up forces = down forces, Then    400 +B = 320 + 560 Then B = 480 N

Q5

The centre of mass of the wheel is at the centre of the circle. The weight acts down along that point.

The tyre is touching the ground at a higher point. The support force is acting up here.

The two forces form the couple.



M

Magnets


Q.1.0

  1. B, 2. C 3. D 4. D.    (24 marks)


Q.2.0

  1. A horse shoe magnet.

  2. C.

  3. No change.

  4. A current will flow from e to d.            6x4=24 marks.


Q.3.0

 .

  1. a.North pole.b. Direction of current. c. North pole.  d. South pole.

  2. a   Decrease,  b  Increase    c No change  d  Increase.

  3. a   Magnetic poles will change.     b. The field will be stronger.

6x3 = 18 marks.

Q.4.0

1.AC. cannot produce electro magnetism as the direction of current changes 50 times a second.

2. Aluminium is not ferromagnetic and cannot increase the magnetic field.

3. As wires are not insulated, the current gets short circuited.

4. Both coils have been wound in the same direction. Same pole will be formed in both arms.

Q.5.0

1.EB.jpg2.

1.Current comes from the battery to the contact breaker.

2.it passes on to the magnet and completes the circuit.

3.The magnet pulls the striker which sounds the bell.

4.The above action breaks the circuit.

5. The sttel blade pulls the striker back completing the circuit.


Mixtures and Compounds

ANSWERS 1.0

1

2

3

4

5

6

7

8

9

10

F

H

L

A

B

K

D

C

E

G


11

12

13

14

15

I

J

M

O


     2.0

      If there are more than 2 words for an answer any 2 may be marked correct.

    1. Leaves, salt, lime, Onion,   2. Water, Clay, salts organic matter.      3.   Water, Tea, sugar, milk.

    4. Cement, water, stones ,      5. Carbon, sulphur, potassium nitrate.     6. Sand, clay, water. Air, organic matter. 7. Water, salts, glucose, cells,    8. Milk, sugar,  Colours, flavour.  9. Pigment, solvent, additives.   10. Carbohydrates, Proteins, Fats, water, minerals, vitamins.

      3.0 

  1. Potassium, Chlorine ,Oxygen,      2.  Hydrogen, Nitrogen Oxygen,     3.  Carbon. Hydrogen, Oxygen.

   4. Carbon,Hydrogen,  Oxygen,             5. Sodium, Carbon, Oxygen          6. Hydrogen, Carbon, Oxygen,   7. Iron, Oxygen, Hydrogen.                  8.  Calcium. Carbon, Oxygen,        9. Sodium, Silicon, Oxygen ( Sometimes   Potassium, lead and some others are also included)     10.   Calcium, Hydrogen, Oxygen.

      4.0 

      1. True        2. True     3 False          4. False            5.  True.

5.0

  1. Name

Solubility

Filtration

Evaporating filtrate

X  Sand

Insoluble

Physical

Physical

Y  Flour

Partly soluble

Physical

Physical

Z  Sugar

Soluble

Physical

Chemical

N

O

P

Q

Screw driver

1.  b.    2. d,  3. a.  4. b   5.  d  6.    c.    7  .  a.  8. b. 9 . d.  10.   b

Sound and Hearing.

Q.1.0

1.Ear canal. 2.Ear membrane. 3.Hammer. 4.Anvil 5. Stirrup. 6.Semilunar canal. 7.Nerves. 8.Cochlea.

9. Eustachian tube. 10.Pinnae.

.

Q.2.0

In what form does a sound signal  1. Reaches the ear.

2.travels in the ear canal  3. In the Middle ear  4. In the Inner ear  5  in the nerves.


Q.3.0

1.particles / molecules.

2. Horizontally  / to right and left.

3. D.

4. Six.     5. 12 Hz.   

6.  V = f x λ …………………….λ = V/f…………...λ = 340/ 12…= 28.33m.

7. 12 oscillations in 1 s.

    1    oscillation in  1/12 s……..=0.083,s.

8. No / In audible. We hear 20Hz to 20 thousand Hz only.

9. Some will be absorbed while some will get rfelected. A few may even pass through.

10. It funnels the waves into the ear canal.

Q.4.0

  1. C.     2.  B.    3. B.


Q.5.0

The list below shows different origins of sound waves. Mention what primarily vibrate in producing these.

  1. A tuning fork. - The two prongs or forks,

  2.  A whistle.-- Air molecules.

  3. A baby crying.-- Vocal Cords and air.   

  4. Lightning  --  Air molecules.

  5. Guitar.-- Wire.

      6. Loud speaker-- The cone  / diaphragm ./ a disc.

T

U

V

W

Answers

1.0.1. Amplitude.  2. Wave length.  3. Wave length,  4. Frequency.   5. Velocity

2.0

1.

2.

Part No.

Blue

Red

Part No.

Blue

Red

4 cm.

2 cm.

a

none

d

b

0.05 s.

0.025 s.

b

b

c

c

20 Hz.

40 Hz.

c

a

d

d

80cms-1

80 cms-1

d

b

c


Q.3.0


A a.jpg



A3b.jpg



Q.4.0

4.1

4.2

4.3

4.4

4.5

Direction.

Wavelength

Velocity

Frequency

Amplitude.

Not changed.

Shortened

Reduced.

Not changed

Increased.


X

Y

Z

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