These Sample papers are part of CBSE Sample Papers for Class 10 Science. Here we have given CBSE Sample Papers for Class 10 Science Paper 15.
CBSE Sample Papers for Class 10 Science Paper 15
Board | CBSE |
Class | X |
Subject | Science |
Sample Paper Set | Paper 15 |
Category | CBSE Sample Papers |
Students who are going to appear for CBSE Class 10 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 15 of Solved CBSE Sample Paper for Class 10 Science is given below with free PDF download solutions.
Time Allowed: 3 hours
Max. Marks: 80
General Instructions:
- The question paper comprises two sections, A and B. You are to attempt both the sections.
- All questions are compulsory.
- All questions of Section-A and B are to be attempted separately.
- There is an internal choice in three questions of three marks each, two questions of five marks each and one question
- (for assessing the practical skills) of two marks.
- Question numbers 1 and 2 in Section-A are one mark question. They are to be answered in one word or in one sentence.
- Question numbers 3 to 5 in Section- A are two marks questions. These are to be answered in 30 words each.
- Question numbers 6 to 15 in Section-A are three marks questions. These are to be answered in about 50 words each.
- Question numbers 16 to 21 in Section-d are five marks questions. These are to be answered in 70 words each.
- Question numbers 22 to 27 in Section- B are based on practical skills. Each question is a two marks question. These are to be answered in brief.
SECTION-A
Question 1.
Name the causative agent of the disease ‘Kala-azar’ and its mode of asexual reproduction.
Question 2.
What steps would you suggest to help minimise environmental pollution caused by burning of fossil fuels?
Question 3.
What are amphoteric oxides? Choose the amphoteric oxides from amongst the following oxides:
Na2O, A12O3, ZnO, CO2 K2O
Question 4.
- What is the fate of the ovules and the ovary in a flower after fertilisation?
- How is the process of pollination different from fertilisation?
Question 5.
The sun appears oval (or flattened) at sunrise and sunset, but appears circular at noon. Explain, why?
Question 6.
How would you distinguish between baking powder and washing soda by heating?
Question 7.
When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.
OR
Translate the following statements into chemical equations and balance them:
- Lead nitrate reacts with sulphuric acid to form a precipitate of lead sulphate and nitric acid.
- Magnesium burns in the presence of nitrogen to form magnesium nitride.
- Aluminium metal strip is added in hydrochloric acid to produce aluminium chloride and hydrogen gas.
Question 8.
Group 13 |
Group 17 |
— | B |
— | C |
— | — |
A | D |
Using the given part of the periodic table, answer the following questions:
- Compare the electro negativities of A and D.
- What is the valency of element D?
- Out of the element given above, name the most non-metallic element in group 17.
Question 9.
- Identify the phytohormone used by plants while performing the following functions:
- Cell division in shoot tip
- Inhibiting growth on approach of unfavourable conditions.
- List in tabular form two differences between the movement in touch me not plant and movement of shoot towards light.
Question 10.
- A nerve input signal travelled only up to the spinal cord and gave output signal for a response. What type of action did the body show, voluntary or involuntary?
- Draw a nerve pathway for the above action and suggest specific terms for input nerve and output nerve.
OR
State the function of receptors in our body. Think of any three situations where receptors in the body do not work properly. Mention the problems which are likely to arise.
Question 11.
Farmers are using a large number of pesticides and fertilisers in their fields to increase crop production and to enhance their profits. But by doing so, they are causing damage to the soil as well as to the environment. Answer the following questions based on the above situation:
- Use of pesticides and fertilisers should be restricted. Do you agree with this statement?
- Why should we avoid eating fruits and vegetables without washing them properly?
- What values are neglected by the farmers?
Question 12.
State reasons for the following:
- Tungsten is used for making bulb filaments.
- Copper and aluminium are generally used for electricity transmission.
- Alloys are commonly used in electrical heating devices such as electric iron and toaster.
Question 13.
“Resistance of an incandescent filament of a lamp is comparatively much more than that when it is at room temperature, why? List two factors on which the resistance of a wire depends. Will the current flow more easily through a thick or thin wire of the same material and length when connected to the same source. Give reason to justify your answer.
OR
Draw a schematic diagram of a circuit consisting of a battery of five 2V cells, a 5 ohm, a 10 ohm and a 15 ohm resistor and a plug key all connected in series. Calculate the electric current passing through the above circuit when the key is closed.
Question 14.
Name the wastes which are generated in your house daily. What measures would you take for their disposal?
Question 15.
List two main causes of the pollution of water of the river Ganga. State how pollution and contamination of river water prove harmful for the health of the people of neighbouring areas.
Question 16.
Give the characteristic tests for the following gases:
- CO2
- SO2
- O2
- H2
Question 17.
Look at the figure and answer the following questions:
- What change would you observe in the calcium hydroxide solution taken in tube B?
- Write the reaction involved in A and B respectively.
- If ethanol is given instead of ethanoic acid, would you expect the same change? Sono
- How can a solution of lime water be prepared in the laboratory?
OR
- What are hydrocarbons? Give examples.
- Give the structural differences between saturated and unsaturated hydrocarbons with two examples each.
- What is a functional group? Give examples of four different functional groups.
Question 18.
Draw the diagram of sectional view of human heart and on it name and label the following parts:
- The chamber of the heart that pumps out de-oxygenated blood.
- The blood vessel that carries away oxygenated blood from the heart.
- The blood vessel that receives de-oxygenated blood from the lower part of our body.
OR
- Draw the human respiratory system and label the following-lung, bronchi, alveolar.
- During breathing cycle what is the advantage of residual volume of air in lungs? Explain.
Question 19.
Give the basic features of the mechanism of inheritance.
Question 20.
- An object of height 4 cm is placed at a distance of 15 cm in front of a concave lens of power 10D. Find the size of the image.
- Draw the following diagrams in your answer book and show the formation of the image of object AB by completing the ray diagrams.
Question 21.
- Explain Fleming’s left hand rule.
- With the help of a diagram, describe an activity to show the force experienced by a current carrying conductor placed in a magnetic field.
SECTION-B
Question 22.
On adding a few drops of universal indicator to three unknown colourless solutions (P), (Q) and (R) taken separately in three test tubes shown in the following diagrams, a student observed the changes in colour as green in (P), red in (Q) and violet in (R). What will be the decreasing order of pH?
Question 23.
Mohan took 5 g of zinc granules in a dry test tube and added 7 g of ferrous sulphate crystals to it. Does he observe any reaction? If not, why?
Question 24.
While preparing a temporary mount of leaf peel to show stomata, Ankita put the coverslip on the peel taken on the slide directly in hurry. She could not observe stomata clearly using microscope. Mention the mistake made by her , and the way to correct the mistake.
Question 25.
The following is the labelled diagram of the structure of a bean seed.
- What is the wrongly labelled part?
- What is the function of seed coat?
Question 26.
In the below set-up, the focal length of the concave mirror is 4.0 cm. Where should the screen be placed on the scale to obtain a sharp image?
OR
An identical prism is stuck to the first prism using a transparent adhesive with the same refractive index as the glass. This is shown in figure. In this figure, draw the path of the ray after it has reached B and until it has passed into the air again.
Question 27.
The following apparatus is available in a laboratory.
- Cell : Adjustable from 0 to 4.5 volt
- Resistors : 3Ω and 6Ω
- Ammeters : A1 of Range 0 to 3 A; Least count 0.1 A
A2 of Range 0 to 1 A; Least count 0.05 A - Voltmeters : V1 of Range 0 to 10 V; Least count 0.5 V
V2 of Range 0 to 5 V; Least count 0.1 V
Find the best combination of voltmeter and ammeter for finding the equivalent resistance of the resistors in series.
Answer
SECTION-A
Answer 1.
The causative agent is Leishmania and its mode of asexual reproduction is binary fission.
Answer 2.
- Use of smokeless appliances
- Afforestation
Answer 3.
Metal oxides which react with both acid and base to produce salt and water are amphoteric oxides. Al2O3, ZnO are amphoteric oxides.
Answer 4.
- After fertilisation, ovules become seeds and ovary forms the fruit.
- Pollination is the transfer of pollen grains from anther to the stigma of a flower whereas fertilisation is the fusion of male and female gametes.
Answer 5.
At sunrise and sunset, the sun is near the horizon. The rays of light from the upper part and lower part of the periphery of the sun bend unequally on traveling through earth’s atmosphere. That is why the sun appears oval or flattened at the time of sunrise or sunset. At noon the sun is overhead. The rays of light from the sun enter’s earth’s atmosphere normally. Therefore they suffer no refraction or bending on passing through earth’s atmosphere. Hence, the sun appears circular at noon.
Answer 6.
The chemical formula of baking powder is sodium hydrogencarbonate (NaHCO3); whereas, that of washing soda is sodium carbonate decahydrate (Na2CO3.10H2O).
Sodium hydrogencarbonate on heating gives CO, gas which will turn lime water milky whereas no ‘such gas is obtained on heating sodium carbonate.
2NaHCO3 \(\underrightarrow { Heat }\) Na2CO3 + H2O + CO2
Na, CO3.10H2O \(\underrightarrow { Heat }\) Na2C03 + 10H2O
Answer 7.
Sodium (Na) and potassium (K) react with cold water to form basic salt NaOH and KOH respectively. The molecular mass of NaOH is 40. So, X is Na and Y is NaOH. The gas liberated during the reaction is hydrogen (H2). So,Z is H7
2Na + 2H7O — 2NaOH + H2 + Heat energy
- Pb(NO3)2(aq) + H2SO4(aq) — PbSO4(s) + 2HNO3(aq)
- 3Mg(s) + N2(8) 4, Mg3N2(s)
- 2Al(s) + 6HCl(aq) — 2A1CI3(aq) + 3H2(g)
Answer 8.
- D is more electronegative than A as electronegativity increases along a period.
- One
- Element B
Answer 9.
-
- Cytokinin
- Abscisic acid
-
S.L. Touch me not plant Shoot tip towards light (a) Movement is fast. Movement is slow (b) No growth of plant part Growth of plant part causes growth
Answer 10.
- Involuntary action was shown by the body.
For input nerve, it is sensory.
For output nerve, it is motor.
OR
- Function of receptors in our body are:
- Receptors are present in our body in all parts, for example in skin, eye,. nose, tongue, etc. They detect the signals and then send them to the brain in the form of electrical signals.
- Receptors help in coordination of all parts and systems of the body.
- If these receptors do not work properly, body will not be able to generate stimulus and action on time which may lead to serious harm to the body as the stimuli will be delayed. For example;
- Hearing impairment may cause serious risk to life on road,
- Inactive gustatory receptors
- Touching of họt object in case of damaged receptor causing burnt hand.
Answer 11.
- Plants require a specific pH range for their healthy growth. By using a large number of pesticides and fertilisers, pH of the soil changes, which makes it more acidic or basic. So, in the long run, the soil becomes infertile. This leads to soil erosion, damaging the environment also. So, use of these pesticides and fertilisers should be restricted.
- The chemical pesticides sprayed by the farmers in their fields, stick to the fruits and vegetables. So, they should be removed by washing properly, before eating.
- Care towards society, unselfishness.
Answer 12.
- Tungsten is a metal which has a very high melting point and comparatively high resistivity.
- Copper and aluminium are good conductors of electricity because they have comparatively low resistivity, i.e., these metals offer low resistance to the flow of electric current.
- Resistivity of alloys is generally higher than that of its constituent metals so it is used in electrical heating devises.
Answer 13.
Resistance of an incandescent filament is more because resistance of a
metallic wire increases with increases in temperature. Resistance of a wire depends upon
- length of wire
- area of cross section of wire
- nature of material of wire (Any two)
The current will flow more easily through the thick wire because \(R\alpha \frac { 1 }{ A }\)
OR
The required circuit diagram is:
Applied potential difference, V = 5 × 2 = 10 V
Total resistance, R= 5 + 10 + 15=30Ω
Current, \(I=\frac { V }{ R } =\frac { 10 }{ 30 } =0.33A\)
Answer 14.
Wastes generated in our house daily are Kitchen wastes, Paper wastęs like newspapers, bags, envelopes,Plastic bags, vegetable/fruit peels.
Measures for disposal are:
- segregation of biodegradable and non biodegradable wastes.
- recycling of paper wastes
- safe disposal of plastic bags
- vegetable and fruit peels should be disposed underground in nearby garden.
Answer 15.
Causes for pollution of water of river Ganga:
- Dumping of untreated sewage
- Industrial wastes
Effects of pollution and contamination of river:
- Growth of disease-causing microorganisms in the river water.
- The river water becomes more acidic which makes the soil acidic and affects the productivity of crops.
Answer 16.
The characteristic test for
- Carbon dioxide (CO2) gas turns lime water milky when passed through it due to the formation of insoluble calcium carbonate.
- Sulphur dioxide (S02) gas when passed through acidic potassium permanganate solution (purple in colour) turns it colourless because SO2 is a strong reducing agent.
- The evolution of oxygen (O2) gas during a reaction can be confirmed by bringing a burning candle near the mouth of the test tube containing the reaction mixture. The intensity of the flame increases because oxygen supports burning
- Hydrogen (H2) gas burns with a pop sound when a burning candle is brought near it.
Answer 17.
- It will turn milky.
- CH2COOH + NaHCO3 — CH3COONa + H2O + CO2 (in A) Ca(OH)2 + CO2 — CaCO3 + H2O (in B)
With excess CO2, milkiness disappears. - As C2H5OH and NaHCO3 do not react, a similar change is not expected
- The lime water is prepared by dissolving calcium oxide in water and decanting the supernatant liquid.
OR
- Compounds of carbon and hydrogen are called hydrocarbons. For example, methane, ethane, etc.
- Saturated hydrocarbons contain carbon-carbon single bonds. Unsaturated hydrocarbons contain at least one carbon-carbon double or triple bond.
- An atom/group of atoms joined in a specific manner which is responsible for the characteristic chemical properties of the organic compounds is called a functional group. Examples are hydroxyl group (-OH), aldehyde group (CHO), ketonic group (C=O), carboxylic group (-COOH), etc.
Answer 18.
- right ventricle
- aorta
- Inferior vena cava
OR
- Residual volume is the amount of air remaining in the lungs after exhalation. It ensures that there is sufficient time for oxygen to be absorbed and for CO, to be released.
Answer 19.
- Characters are controlled by genes.
- Each gene controls one character.
- There may be two or more forms of gene.
- One form may be dominant over the other.
- Genes are present on chromosomes.
- An individual has two forms of gene whether similar or dissimilar.
- The two forms separate at the time of gamete formation.
- The two forms are brought together in the zygote.
Answer 20.
- h1=4 cm, u = -15 cm, P = – 10D, h,=?
Answer 21.
- If forefinger, middle finger and thumb of our left hand are stretched mutually perpendicular in such a way that forefinger points along the direction of magnetic field, middle finger points along the direction of current, then thumb will indicate the direction of force.
- Take a small aluminium rod AB (of about 5 cm). Using two connecting wires suspend it horizontally from a stand, as shown in figure. Place a strong horse-shoe magnet in such a way that the rod lies between the two poles with the magnetic field directed upwards. For this put the north pole of the magnet vertically below and south pole vertically above the aluminium rod (Figure).
- Connect the aluminium rod in series with a battery, a key and a
rheostat. - Now pass a current through the aluminium rod from end B to end A.
- What do you observe? It is observed that the rod is displaced towards the left. You will notice that the rod gets displaced.
- Reverse the direction of current flowing through the rod and observe the direction of its displacement. It is now towards the right.
- This shows that a current carrying conductor experiences a force when placed in a magnetic field.
SECTION-B
Answer 22.
The decreasing order of pH will be R > P > Q. The reason is that the test tube showing green colour has a pH of 7, test tube showing red colour has a pH of 1 and the test tube showing violet colour has a pH of 13.
Answer 23.
No, Mohan does not observe any reaction. This is because an aqueous solution of ferrous sulphate is required.
Answer 24.
- The air bubbles entered the slide due which she was not able to see stomata.
- She should have used glycerine on the peel before placing the cover slip.
Answer 25.
- Seed coat is wrongly labelled.
- Seed coat is the outer covering of seed which protects and cover the seed.
Answer 26.
When the object is kept at infinity in front of a concave mirror, then its image is formed at focus. Here, the focal length of the concave mirror is 4.0 cm. Mirror stand is placed at 5.0 cm mark of the metre scale. Hence the screen should be placed at 1 cm mark on the scale to obtain a sharp image.
OR
Answer 27.
Equivalent resistance, R = 3Ω + 6Ω = 9Ω
Maximum voltage to be measured = 4.5 V
Maximum current to be measured = \(\frac { V }{ R } =\frac { 4.5 }{ 9 } =0.54\)
These requirements of measuring this current and voltage are fulfilled by ammeter A2 and voltmeter V2. Also these two instruments are more accurate due to their smaller least counts 0.05 A and 0.1 V respectively.
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