Science
Std.-10
QUESTION PAPER - 4
Total Mark : 80
Time : 3 Hours
Section-A
Answer the following Q. No. 1 to 18 (within the limit of 10 to 20 words) as directed:(1 mark each)
Fill in the blanks so as to make each of the following statements true :
1. Electric potential at a point in an electric field is measured as the ..work.. done in
bringing, a unit positive test charge from infinity to that point,
2....cerebrospinal..... fluid is found in ventricles of brain.
3..cerebellum.... is a part of hind brain which maintain the posture and balance of body.
4. Atomic size .decrease....from left to right in a period.
State whether the following statement are true or false.
5. Oxidation is the loss of electrons from a substance.True
6. The reaction of ethanol with conc. H2SO4 gives ethane.False
7. Carboxylic acids react with alcohols to form esters.True
Choose the correct option and write it with answer from those given below multiple
choice questions : (MCQs)
8. The three R's that will help us to conserve natural resources for long Term use are
(a) recycle, regenerate, reuse (b) reduce, regenerate, resuse
(c) reduce, reuse, redistribute (d) reduce, recycle, reuse
9.Organisms which synthesise carbohydrates from inorganic compounds using radiant energy are called
(a) decomposers (b) producers (c) herbivores (d) carnivores
10. Fuel used in thermal power plants is
(a) Water (b) Uranium (c) Biomass (d) Fossil fuels
11. In human males all, the chromosomes are paired perfectly except one.
This/these unpaired chromosome is/are
(i) Large chromosome (ii) Small chromosome
(iii) Y-chromosome (iv) X-chromosome
(a) (i) and (ii) (b)(iii) only
(c)(iii) and (iv) (d) (ii) and (iv)
Answer the following questions as directed :
12. Which part of the human eye helps in changing the thickness of lens?ciliary muscles
13. What is meant by F1 generation? First pregnancy
14. Write the name and symbol of the element from the description. The atom having smallest atomic mass.hydrogen
15.Which waves do not require material medium for propagation? electromagnetic waves
16. What is the age of puberty in human males? 12 - 14 year
Section : B
following questions Q. no. 17 to 26 (within the limit of 40 to 50 words) as
directed : (2marks each)
17. Explain properties and uses of Baking soda.
Properties Of Baking Soda
★ It Is Non flammable.
★Powder Dust Is Not as Explosive.
★It Has the temperature Of 50°.
★It is Basic In Nature.
★It is White crystalline.
★It is Odourless.
Uses:-
★Ruduce The acidity In stomach.
★Used In The Process Of Washing As a Water Softener.
18. What are amphoteric oxides? Give two examples of amphoteric oxides.
Compare the radii of two species X and Y. Give reasons for your answer.
a. X has 12 protons and 12 electrons
b. Y has protons and 10 electrons
Answer:X is bigger and Y is smaller
Explanation: as there are more shells in X (2 ,8,2) the effective nuclear charge is less.hence it is smaller in size
And ther is less no. Of shells in Y (2,8) so the effective nuclear charge is more.hence it is bigger in size.
OR
19.An element X with 18 neutrons has mass number 35. Write atomic number and elecronic configuration of X. Also write group number, periodic number and valency of X.
Ans :- Atomic number of element x is 17 and electronic configuration is 2,8,7 and group number is 17 and period number is 3 and valency is 1.
20.What are the difference between autotrophic nutrition and heterotrophic nutrition?
Ans :- Autotrophic nutrition :
1.Organism prepares its own food.
2.It is independent for its food requirements.
3.eg :green plants
Heterotrophic nutrition :
1.Organism does not prepare its own food.
2.It depends on plants for food requirements
3.eg :animals,human beings etc.
OR
20. List in tabular form, three differences between arteies and veins.
Ans : {Arteries}
⏩ It carry blood away from the heart to various organs of the body.
⏩ It have thick and elastic walls.
⏩ It doesn't have valves.
{Veins}
⏩ It collect blood from different organs and bring it back to heart.
⏩ It doesn't have thick and elastic walls.
⏩ It have valves to ensure that the blood flows only in one direction.
21.Why is variation beneficial to the species but not necessarily for the individual?
Ans :-The variation is important and beneficial for species as it allows a species to adapt to a changing environment.
For example, climate change can force a species to shift its range to poleward or to higher altitudes.
Only those who adopt the changes can survive in harsher conditions by adapting to the changes.
For an individual, the variation doesn't matter in most of the conditions.
22.State the laws of refraction.
Ans :- The two laws of refraction are:-
1.the normal , incident Ray and refrected Ray lie at same plane.
2.sini/sinr=constant
the ratio of sin of angle of incident with sin of angle of refraction is constant.
23. To study the variation of current in series combination of resistance.
OR
23.An electric iron has a rating of 750 W, 220 V. Calculate the
a. Current flowing through it and
b. Its resistance when in use.
GIVEN:
Power=750w
V=220volts
P=Vx I
I=P/V
=750/220
=3.40A
By ohm's law, we have V=IR
R=V/I
=220/3.40
=64.7 OHMS.
THEREFORE, The current passing through circuit is 3.40A and Resistance =64.7 OHMS.
24. How does alternating current differ from the direct current ?
Ans : - Alternating current (AC) is a type of electric current that flows in two directions- forwards and backwards. Direct current (DC) is a type of electric current that only flows in one direction.
Uses of alternating current (AC) are in producing and transporting electricity. Nearly every home in the world is powered through the use of AC current.
Direct current (DC) is mainly used in batteries, as once the current has run out, the batteries have to be replaced, because the current can only flow in one direction.
25. What are the components of ecosystem?
Ecosystem is a natural process with natural resources and abiotic factors such as sunlight, soil, water and all nonliving things
Components of the ecosystem are the abotic factors that biotic factors which are living things.
26. What is meant by wildlife? How is wildlife important for us?
Explanation: Wildlife Conservation is the practice of protecting wild plant and animal species and their habitats. Wildlife plays an important role in balancing the environment and provides stability to different natural processes of nature.
It is important to us
Wildlife Conservation is the practice of protecting wild plant and animal species and their habitats. Wildlife plays an important role in balancing the environment and provides stability to different natural processes of nature.
OR
26. What is 'Chipko Movement?
Ans:- Chipko movement is a non - violence based on Gandhian principle introduced to conserve trees from being cut by covering trees with body.
Section : C
Answer the following Q. no. 27 to 34 in short (within the limit of 60 to 80 words) as
directed. (3 marks each)
27. To prepare copper oxide and to show the redox reaction of copper oxide with hydrogen gas.
27. To prepare copper oxide and to show the redox reaction of copper oxide with hydrogen
gas.
Aim :- To prepare copper oxide and show the redox reaction of copper oxide with
hydrogen gas.
Materials required.
Copper powder, glass tube (50 cm), China digh
watch glass, tongs, bored rubber cork, burner, dil. HCI, containing
laboratory stand, clamp,Wire gauze,-Tripod stand
Procedure: -1. Prepare copper oxide in a china dish by heating
copper powder in presence of O2(g) as shown in Fig. 1.15(a).
2. Take a glass tube 50 cm long.
3. Fix it horizontally on a laboratory stand with the
help of clamp as shown in Fig. 1.15(a).
4. Close both the ends of the glass tube with bored
rubber cork and insert the glass tubes as shown
in Fig. 1.15(b).
5. Pass hydrogen gas over heated copper oxide.
6. Note down the observations.
Observation. The surface of copper powder becomes coated with black copper (II) oxide.
Bumer
Chemical Reaction and Explanation. It is because copper reacts with oxygen on heating to form
copper oxide which is black.heat
2Cu (s) + O2(g) - > 2Cuo (s)
Copper Copper (Il) oxide
(Reddish brown) (Black)
Now pass the hydrogen gas prepared by reaction of zinc metal with dil. H2SO4 over the
heated copper oxide.
Record the observations after sometime.
Observation. The black coating on the surface furns pink (reddish brown).
Chemical Reaction and Explanation. Copper oxide reacts with hydrogen gas to form reddish
brown copper and H2O.
Oxidation
CuO (s) + H2 (g) -> Heat, Cu (s) + H2O
Reduction
During this reaction, the copper (II) oxide is losing oxygen and is being reduced. The hydrogen
is gaining oxygen and is being oxidised.
Conclusion, The reaction between copper oxide and H, is redox reaction. Copper oxide is oxidising
agent whereas H2 is reducing agent.
28. To compare the reactivity of different metals towards water.
Explanation:
When potassium reacts with water it directly forms its Hydroxide and cathes fire immediately
K+H2O=KOH+O2
When calcium reacts with water it forms Hydroxide and starts floating.
Ca+H2O=Ca(OH) 2+H2
Iron reacts with steam only. It forms its oxide only
Fe+H2O=FeO+h2
OR
28. Write the various properties of ionic compounds.
Properties of Ionic Compounds
Ionic Compounds have high boiling and melting points as they’re very strong and require a lot of energy to break.
The electrostatic forces of attraction between oppositely charged ions lead to the formation of ions.
Ionic compounds form crystals.
These compounds are brittle and break into small pieces easily.
Electrovalent compounds usually dissolve in water and are insoluble in solvents like oil, petrol, kerosene, etc.
Ionic compounds do not conduct electricity in a solid-state but they do conduct electricity in the molten state.
In comparison to molecular compounds, ionic compounds have higher enthalpies of fusion and vaporization.
29. Mention the function of adrenaline hormone.
Adrenaline is secreted when the animal is faced with a fight-or-flight situation, ie the animal can fight to defend itself or run away from the threat.
both actions are complex actions that require a variety of changes in the body.
adrenaline targets the body parts that are useful in both actions.
it directs extra blood flow towards muscles in arms, legs, lungs as these are most useful in fight or flight to ensure they are working at maximum capacity.
this blood is directed away from digestive system towards arms, legs, lungs as digestive system is not helpful in running or fighting.
30. Give differences between asexual and sexual modes of reproduction.
Explanation:
Sexual Reproduction- is a mode of reproduction in which formation & fusion of gametes take place.
The offspring produced are not identical to their parent or to each other, hence, it leads to variation in population .
It is an elaborate, complex, & slow process.
It is usually biparental & involves meiosis .
Plays a vital role in evolution .
Common in higher animals with complex organisation.
Asexual Reproduction - does not involve formation or fusion of gametes.
The offsprings produced are genetically identical to their parents & referred to as clones .
It is simple, & fast process.
It is always uniparental & involves only mitosis .
It does not play important role in evolution .
Common among single celled organisms & in plants & animals with relatively simple organisation.
31. How is the sex of the child determined in human beings?
The sex of a child depends on the kind of sperm that fertillizes the egg. the egg contains only one X chromosome , but half of the sperms released into the female are X bearing and the remaining half are Y bearing.
___________________________
its simply a matter of chance as to which category of sperm fuses with the ovum .
1)if the egg(X) is fused by X-bearing sperms the resulting combination is XX ie a female type and the chlid produced is female.
2) if the egg (X) is fused by Y bearing sperm , the resulting combination is XY i.e. male type and the child produced is a male
32. To determine the principal focus and rough focal length of a convex lens.
AIM: To determine the focal length of a convex lens by obtaining an image of a distant object.
Apparatus/Material Required : A convex lens, convex lens stand, a small screen (hard sheet of white paper/cardboard) fixed to a stand, a measuring scale.
Procedure :
1. Fix the convex lens on the lens holder or stand and place it place it on the table near an open window of the laboratory.
2. Locate a distant tree/building from the open glass window (if an open window is not available then obtain the image of the window itself on the screen.
3. Place the screen behind the convex lens.
4. Adjust the position of the convex lens and the screen so that a sharp, inverted and diminished image of a distant object is formed clearly on the screen.
5. Note the positions of the screen and the convex lens stand with the help of measuring scale.
6. Find the distance between the optical centre of the lens and the screen. This distance is equal
to the focal length of the convex lens. Record the the focal length.
7. Repeat the experiment a few times by changing the positions of the convex lens stand and note the corresponding changed position of the screen.
8. Calculate the mean value of the focal length.
Observation and Calculation:
S.No. Position of the Position of the Focal length of the convex lens white screen (Q) concave mirror (Q-P) (P) (in cm) (in cm) (in cm) 1 _______ _______ f1 = ——– 2 _______ _______ f2 = ——— 3 _______ _______ f3 = ———- 4 _______ _______ f4 = ———– Mean value of focal length of concave mirror f = f1+f2+f3+f4 4 = ——— cm
OR
32. To show that the apparent depth of a coin at the bottom of a bucket filled with water is
less than the real depth of the coin in the water.
1) The depth appears to be less because of refraction of light.
Light coming from the bottom of the bucket gets refracted and
we percieve the depth to be lesser.
2) Consider the following example. I have taken coin for
simplifying the diagram.
3) The light coming from the coin placed at the bottom gets
refracted away from the Normal because of refraction.
4) So, instead of appearing at its real depth, it appears raised.
The same phenomenon is applicable to the bottom of the bucket
itself. Hence, the bottom appears raised and we see that the
bucket is filled slightly less than it actaully is.
33. To verify Ohm's law.
Aim
To study the dependence of potential difference (V) across a resistor on the current (I) passing through it and determine its resistance. Also plot a graph between V and I.
Materials Required
A battery, an insulated copper wire (cut into 10 pieces), a key, an ammeter, a voltmeter, a rheostat, a resistor and a piece of sand paper.
Procedure
Keep the devices as shown in the circuit diagram.
Connect them with the connecting wires and keep the key open.
Positive terminal of the battery is connected to the positive terminal of the ammeter.
Check the +ve and -ve terminals of voltmeter before connecting it in the circuit.
Once the circuit is connected, insert the key and check the rheostat, adjust its slider and see whether the ammeter and voltmeter readings are shown.
By using the slider of rheostat take three different readings of current 1 and voltmeter V.
Record your observations in the observation table.
Calculate resistance of a given resistor by formula R= { V }{ I }.
Plot a graph of voltmeter reading and current reading. On x axis take V and on y axis take I.
Resistance increases with increase in temperature of pure metals.
Observation table
For reading of ammeter and voltmeter
S.N (I) (v) R =V/I(Ω)
1. 0.02 0.04 R1 =2 Ω
2. 0.03 0.06 R2= 2 Ω
3. 0.04 0.08 R3 = 2Ω
34. a. What is a solar water heater?
Solar water heaters use the solar energy from the sun to generate heat (not electricity) which can then be used to heat water for showering, space heating, industrial processes or even solar cooling.
b. Mention advantages of solar water heaters.
they use solar energy which is a free, renewable source of energy
- by using solar energy they help reduce our dependence on fossil fuels
- in sunny and warm places with high insolation values solar water heating systems are highly cost effective
- many countries around the world offer favorable incentives for the installation of solar water heating systems
- relatively good payback period, in average between 5-10 years
- low maintenance costs
- you can build your own solar water heating systems
- some countries even offer the option of leasing solar water heating systems which can significantly decrease initial costs
Section : D
Answer the following Q. no. 35 to 39 in detail (within the limit of 90 to 120 words) as
directed : (4 marks each)
35. Draw the electron dot structures of the following compounds:
a. Cyclopentane
c. Ethene
b. Butyne
d. Sulphur molecule
a. Cyclopentane
c. Ethene
b. Butyne
d. Sulphur molecule
36. Draw and explain human heart.
Structure of Human Heart
The heart is a muscular organ covered by a double membrane called pericardium. The pericardial fluid of the pericardium lubricates the heart. The heart is divided into four chambers two upper atria and two lower ventricles. The inter-atrial septum separates the two atria and the inter-ventricular septum separates the two ventricles. The atrium and the ventricle of each side are separated by the atrioventricular septum. Superior and inferior vena cavae open into the right atrium. The right ventricle opens into the pulmonary artery. Four pulmonary veins open into the left atrium.The left ventricle opens into the aorta. The opening between the right atrium and right ventricle is guarded by the tricuspid valve.The opening between the left atrium and left ventricle is guarded by the bicuspid (mitral) valve. The opening of the right ventricle into the pulmonary artery and the opening of the left ventricle into the aorta is guarded by the semilunar valves.
Working of Heart
The right atrium receives blood from the upper and lower body through the superior vena cava and the inferior vena cava, respectively, and from the heart muscle itself through the coronary sinus. The right atrium is the larger of the two atria, having very thin walls. The right atrium opens into the right ventricle through the right atrioventricular valve(tricuspid), which only allows the blood to flow from the atria into the ventricle, but not in the reverse direction. The right ventricle pumps the blood to the lungs to be reoxygenated. The left atrium receives blood from the lungs via the four pulmonary veins. It is smaller than the right atrium but has thicker walls. The valve between the left atrium and the left ventricle, the left atrioventricular valve(bicuspid), is smaller than the tricuspid. It opens into the left ventricle and again is a one-way valve.The left ventricle pumps the blood throughout the body through the aorta, which is the largest artery in the body. The walls of the left ventricle are the thickest among all the chambers.
Electric motor: A motor is a device which converts electrical energy into mechanical energy.
Principle of motor : A motor works on the principle that when a rectangular coil is placed in a magnetic field and current is passed through it. A force acts on the coil which rotates it continuously.
When electric current is passed into the rectangular coil, this current produces a magnetic field around the coil.
The magnetic field of horse shoe-type magnet then interacts with the magnetic field of the coil and causes the coil to rotate continuously.
If ABCD is in horizontal position current from battery enters the coil through brush B _{ 1 }, and commutator half ring C:. The current flows in the direction ABCD
and leaves via ring and brush B _{ 2 }
The direction of current is from A to B, the direction of current is from C to D. The force on side AB of the coil is in the downward direction. Whereas the force on the side CD of the coil is in the upward direction. ABCD rotate in anti-clockwise direction.
While rotating when the coil reaches vertical position then the brushes B _{ 1 } and B _{ 2 } will touch the gap between the commutator rings and current to the coil is cut off. But the coil does not stop rotating because it has already gained momentum.
The coil CD comes on the left side and AB comes to the right side. Again they come in contact with brush B _{ 1 } Current direction is reversed.
The reversing of current in the coil is repeated after every half rotation due to which the coil continue to rotate as long as current from the batter is passed through it. The rotating shaft of electric motor can drive a large number of machines which are connected to it
OR
37.To study the relationship between direction of current,magnetic field and motion (force acting on a conductor) of a conductor.
To study the force on a current-carrying straight conductor in a magnetic field and to verify that the motion of the conductor is according to Fleming’s left-hand rule.
Theory:
A current carrying conductor placed in a magnetic field experiences a force. If the direction of the field and that of current are mutually perpendicular to each other, then the force acting on the conductor will be perpendicular to both and that can be determined using the Fleming’s left-hand rule. When current establishes in the conductor, it gets displaced which verifies the existence of a force on the conductor.
Fig. (1) - A current-carrying rod, AB, experiences a force perpendicular to its length and the magnetic field
Fleming's Left Hand Rule:
Hold the thumb and the first two fingers of your left hand mutually at right angles to each other as shown in Fig. (1). Then if the Forefinger points in the direction of the Field, and the second finger in the direction of the Current, the thumb will point in the direction of Force
38.Properties and uses:
a. Bleaching powder c. Washing soda
b. Baking soda
Washing soda
1)It is a white transparent crystalline solid. 3)The solution of washing soda in water is alkaline which turns red litmus to blue. 1)It is used to remove permanent hardness of water. 2)It is used in the manufacture of glass,soap,paper.
Uses :-
Used in removing permanent hardness of water
Used in manufacturing sodium compounds like borax
Baking soda
1.Sodium bicarbonate (Baking Soda) is a chemical compound with the formula NaHCO3
2. It is a white solid that is crystalline but often appears as a fine powder.
3. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate).
4. It can be used in Pest Control.
5. It is good fire extinguisher especially for electrical fires.
Uses :-
Used in soda acid fire extinguisher
Used in making baking powder
Bleaching powder
It is produced by the action of Chlorine on dry slaked lime. It is represented as CaOCl2, though the actual composition is quite complex.
Ca(OH)2 + Cl2 → CaOCl2 + H2O
On standing for a longer time, it undergoes auto oxidation due to which bleaching action decreases.
Uses :-
Used in manufacturing chloroform
Used as a disinfectant in swimming pools
OR
38.Design an activity to prove that acids show acidic behavior only when dissolve water.
Answer
If the colour of red litmus paper gets changed to blue, then it is a base and if there is no colour change, then it is either acidic or neutral. Thus, basic solution can be easily identified.
Let us mark the three test tubes as A, B, and C. A drop of the solution in A is put on the red litmus paper. Same is repeated with solution B and C. If either of them changes colour to blue, then it is basic. Therefore, out of three, one is eliminated. Out of the remaining two, any one can be acidic or neutral. Now a drop of basic solution is mixed with a drop of each of the remaining two solutions separately and then the nature of the drops of the mixtures is checked. If the colour of red litmus turns blue, then the second solution is neutral and if there is no change in colour, then the second solution is acidic. This is because acidic and basic solutions neutralize each other. Hence, we can distinguish between the three types of solutions.
39.Defects of vision and their correction.
✔️ Myopia.
✔️ Hypermetropia.
✔️ Presbyopia.
Myopia is also known as near-sightedness. A person with Myopia can see nearby objects clearly but cannot see distant objects distinctly.
This defect arises due to :-
⏩ Excessive curvature of the eye lens.
⏩ Elongation of the eyeball.
This defect can be corrected by using a concave lens of suitable power.
Hypermetropia is also known as far-sightedness. A person with hypermetropia can see distant objects clearly but cannot see near by object distinctly.
This defect arises due to:-
⏩ The focal length of the eye lens is too long.
⏩ The eyeball has become too small.
This defect can be corrected by using a convex lens of appropriate power.
The power of accommodation of eyes usually decreases with ageing. They find it difficult to see nearby objects comfortably and distinctly without corrective eye-glasses. This defect is called Presbyopia.
This defect arises due to:-
⏩ Gradual weakening of ciliary muscles.
⏩ Diminishing flexibility of the eye lens.
This defect can corrected by using bi-focal lenses consists of both concave and convex lenses
Thank you so much, sir
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