AP SSC 10th class General Science Model paper 2015-16 English Medium Set 3
SECTION -I
Group – A
1. Write the rules for sign convention for the parameter related to the mirror equation.
2. The focal length of a converging lens is 20 cm. An object is 60 cm from the lens. Where will the image be formed and what kind of image is it ?
3. Are the headlights of a car connected in series or parallel ? Why ?
4. What is magnetic flux density ? Write it’s units.
Group – B
5. Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid is added to test tube A, while acetic acid is added to test tube B. Amount and concentration of both the acids is same ? In which test tube will the fizzing occur more vigorously and why ?
6. A shiny brown coloured element ‘x’ on heating in air becomes black in colour. Can you predict the element ‘X’ and the black coloured substance formed ? How do you support your predictions ?
7. ‘X’ is an element belongs to ‘3’rd period and 13
th
group then answer the following.
i) Write the electron configuration of ‘X’ ?
ii) What is the valency of ‘X’ ?
8. How do you appreciate the role of esters in everyday life ?
SECTION -II
9. Equal amounts of water are kept in a cap and in a dish. Which will evaporate faster ? Why?
10. Write the mirror formula.
11. What is presbyopia ?
12. What is the use of keeping food in air tight containers ?
13. Represent the molecule H
2
0 using Lewis notation.
14. Name the product other than water formed on burning of ethanol in air.
SECTION – III
Group – A
15. Suggest an experiment to prove that the rate of evaporation of a liquid depends on its surface area and vapour already present in surrounding air.
16. Write the working of optical fibres and also their uses in our daily life.
17. Explain Kirchhoff’s laws with examples.
18. Explain the working of AC electric generator with a neat diagram.
Group – B
19. What is an exothermic reaction ? Why does respiration considered as an exothermic reaction ? Explain.
20. Compounds such as alcohol and glucose contain hydrogen but are not categorized as acids. Describe an activity to prove it.
21. What is hybridisation ? Explain the formation of BF
3
molecule using hybridisation.
22. Suggest a chemical test to distinguish between ethanol and ethanoic acid and explain the procedure.
SECTION – IV
23. Show the formation of image with a ray diagram when an object is placed on the principal axis of a concave mirror away from the centre of curvature.
24. Draw the shapes of five ‘d’ orbitals.
Answers
SECTION -I
Group – A
1. Write the rules for sign convention for the parameter related to the mirror equation.
A.
1) All distance should be measured from the pole.
2) The distance measured in the direction of incident light, to be taken positive and those measured in the direction opposite to incident light to be taken negative.
3) Height of object (H
o
) and height of image (H
i
) are positive if measured upwards from the axis and negative if measured downwards.
2. The focal length of a converging lens is 20 cm. An object is 60 cm from the lens. Where will the image be formed and what kind of image is it ?
3)
Nature of image
: Real and inverted.
Size
: Diminished
Location
: 30 cm from the lens other side.
3. Are the headlights of a car connected in series or parallel ? Why ?
A.
The headlights of a car are connected in parallel.
Reasons
:
1) When they are connected in parallel, same voltage (RD) will be maintained in the two lights.
2) If one of the light damaged, the other will work without any disturbance.
4. What is magnetic flux density ? Write it’s units.
A.1)
Magnetic flux density (B) is defined as the ratio of flux passing through a plane perpendicular to field and the area of the plane.
2) Units of magnetic flux density is Wb/m
2
or Tesla.
Group – B
5. Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid is added to test tube A, while acetic acid is added to test tube B. Amount and concentration of both the acids is same ? In which test tube will the fizzing occur more vigorously and why ?
A.
1) The volatility of acetic acid is more than that of hydrochloric acid. But HC/ solution has more strength than acetic acid.
2) Hence magnesium ribbon in test tube A will react more vigorously in B.
6. A shiny brown coloured element ‘x’ on heating in air becomes black in colour. Can you predict the element ‘X’ and the black coloured substance formed ? How do you support your predictions ?
A.
1) The name of element X is copper (Cu)
2) Name of black coloured substance is copper oxide [CuO]
ii) What is the valency of ‘X’ ?
A.
The valency of aluminium is 3.
8. How do you appreciate the role of esters in everyday life ?
A.
1) Esters are used in making artificial perfumes.
2) This is because of the fact that most of the esters have a pleasant smell.
3) Esters are also used as flavouring agents.
4) This means that esters are used in making artificial flavours and essences used in ice-cream, sweets and cool drinks.
5) That’s why we can appreciate the role of esters in everyday life.
SECTION – II
9. Equal amounts of water are kept in a cap and in a dish. Which will evaporate faster ? Why ?
A.1)
The water in dish has more evaporation than the water in cap.
2) Because, the rate of evaporation is directly proportional to the surface area of the dish.
10. Write the mirror formula.
A.
Mirror formula : 1/f =1/u + 1/v
11. What is presbyopia ?
A.
The ability of accommodation of the eye usually decreases with ageing. This defect is called presbyopia.
12. What is the use of keeping food in air tight containers ?
A.
1) When fats and oils are oxidised they became rancid. Their smell and taste changes.
2) Keeping food in air tight containers helps to slow down oxidation process.
13. Represent the molecule H
2
0 using Lewis notation.
14. Name the product other than water formed on burning of ethanol in air.
A.
Carbondioxide (C0
2
)
SECTION – III
Group – A
15. Suggest an experiment to prove that the rate of evaporation of a liquid depends on its surface area and vapour already present in surrounding air.
A.
Aim
: To prove that rate of evaporation of liquid depends on its surface area.
Apparatus
: Two dishes of different surface area and spirit.
Procedure :
1). Take a small quantity of spirit in two dishes separately.
2) Keep the dishes under the fan and switch on the fan.
3) After some time observe the quantity of spirit in both dishes.
4) It is proved that the dishes contain larger surface area of spirit is fastly evaporated.
5) So, the rate of evaporation of a liquid depends on its surface area.
16. Write the working of optical fibres and also their uses in our daily life.
A.
Working of optical fibres :
1) Total internal reflection is the basic principle for working of optical fibre.
2) Figure shows the principle of light transmission by an optical fibre.
3) Because of the small radius of the fibre, light going into it makes a nearly glancing incidence on the wall.
4) The angle of incidence is greater than the critical angle and hence total internal reflection takes place. The light is thus transmitted along the fibre.
Uses:
1) Optical fibres are used in endoscopy to see the internal organs like stomach, intestines, etc.
2) Optical fibres are used in transmitting communication signals through light pipes.
17. Explain Kirchhoff’s laws with examples.
A. Kirchhoff’s laws
1) Junction Law
: At any junction point in a circuit where the current can divide, the sum of the currents into the junction must equal the sum of the currents leaving the junction.
From the above figure, according to Junction law we have I1 + I
4
+ I
6
= I
5
+ I
2
+ I
3
2) Loop Law
: The algebraic sum of the increases and decreases in potential difference across various components of a closed circuit loop must be zero.
18. Explain the working of AC electric generator with a neat diagram
.
A.
1) Consider initially the coil, positioned in such a way that magnetic flux passes through it. When the coil is at rest in vertical position, with side (A) of coil at top position and side (B) at bottom position, no current will be induced in it. In this position, the current in the coil is zero.
2) When the coil is rotated in clockwise direction, current will be induced in it flows from A to B. During the first quarter of rotation, the current increases from zero to a maximum and reaches peak value when the coil is in horizontal position.
3) If we continue the rotation of coil, current decreases during second quarter of the rotation and once again becomes zero. When coil comes to vertical position with side B at top and side A at bottom. During second part of the rotation. Current generated follows the same pattern as that in the first half, except that the direction of current is reversed.
4) This current is called Alternating Current (AC).
Group – B
19. What is an exothermic reaction ? Why does respiration considered as an exothermic reaction ? Explain.
A.
Exothermic reaction
: A reaction in which heat energy is released by the reactants is called an exothermic reaction.
1) By the respiration oxygen is taken in and it is combine with glucose which is in blood.
2) This glucose combine with oxygen in the cells of our body and releases energy, C0
2
and water which helps to do the various works.
3) C
6
H
12
0
6
+ 60
2
—» 6C0
2
4- 6H
2
0 + energy.
4) In this reaction energy is also released, hence it is an exothermic reaction.
20. Compounds such as alcohol and glucose contain hydrogen but are not categorized as acids. Describe an activity to prove it.
A.
1) Prepare solutions of glucose, alcohol and hydrochloric acid etc.
2) Connect two different coloured electrical wires to graphite rods separately in a 100 ml beaker as shown in figure.
3) Connect free ends of the wire to 230 volts AC plug and complete the circuit as shown in the figure, by connecting a bulb to one of the wires.
4) Now pour some dil. HCl in the beaker and switch on the current.
5) You will notice that the bulb glows in acid solution (HCl). Because Acid solutions produce H
+
ions and these ions one responsible for the flow of current.
5) Repeat same activity with glucose and alcohol solutions separately. In glucose and alcohol solutions the bulb did not glow. This indicate the absence of ions in these solutions.
Hence glucose and alcohol are not categorized as acids.
21. What is hybridisation ? Explain the formation of BF
3
molecule using hybridisation.
A. Hybridisation
: It is a phenomenon of inter mixing of atomic orbitals of almost equal energy which are present in the outer , shells of the atom and their reshuffling or redistribution into the same number of orbitals but with equal properties like energy and shape. This process is called hybridisation.
Formation of BF
3
molecule :
- There is an inter-mixing of 2s, 2p x , 2p y orbitals and their redistribution into three identical orbitals called sp 2 hybrid orbitals.
- It is suggested that excited ‘B’ atom undergoes hybridisation
- As it forms three identical B-F bonds in BF 3 .
- The excited electronic configuration of S B is Is 2 2s 1 2p x 1 2p h
- 5 B has electronic configuration 1s 2 2s 2 2p x 1
- For three sp 2 orbitals to get separated to have minimum repulsion the angle between any two orbitals is 120° at the central atom and each sp 2 orbital gets one electron.
7. Now three fluorine atoms overlap their 2p
z
orbitals containing unpaired electrons (F
9
Is
2
2s
2
2p
x
2
2p
y
2
2p
z
!
) the three sp
2
orbitals of’B’ that contain unpaired electrons to form three ssp
2
-p bonds.
22. Suggest a chemical test to distinguish between ethanol and ethanoic acid and explain the procedure.
A.
1) Take ethanol and ethanoic acid in two different test tubes.
2) Add nearly 18m of sodium bicarbonate (NaHC0
3
) to each test tube.
3) Lots and lots of bubbles and foam will be observed from the test tube containing ethanoic acid. This is due to release of C0
2
.
NaHC0
3
+ CH3COOH ® CH
3
COONa + H
2
0 + C0
2
4) Ethanol will not react with sodium bicarbonate and thus we won’t observe any change in the test tube containing ethanol.
Thus we can seperate ethanol from ethanoic acid.
SECTION – IV
23.Show the formation of image with a ray diagram when an object is placed on the principal axis of a concave mirror away from the centre of curvature.
A.
When the object is placed away from the centre of curvature on the principal axis, the image will form between C and F
OJ = Object
JM = Parallel incident beam
F = Focus
P Polo
MG, M’G = Reflected rays
IG = Image (Real, inverted and
diminished.
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