Science Sample paper 3 of class Xth -2021 (fully updated)

Science Sample paper class -Xth

                             

Section-A

Time 50min .                                     Mm:-32

1.Explain emulsification.

Or

.Which part of alimentary canal receives bile from the liver .

2.Where is the magnetism of a bar magnet maximum and minimum.

3.An element 'Z' belongs to 3rd period and group 17 of the periodic table. What is it's valency and justify your answer.

4.Why are the danger signals installed at the top of tall buildings red in colour.

5.The following figure shows a ray of light travelling from medium A to medium B. Determine the refractive index of the medium B relative to medium B. 

Or 

The speed of light in a transparent medium is 0.6 times that of it's speed in vacuum.

What is the refractive index of the medium?

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6.Quick lime reacts with water ,what will it give?

Or

In the given reaction,

Na2CO3 +xHCl---------->2NaCl +CO2+H2O,

what is the value of x?

7.A reactive metal (M) is treated with Dil.H2SO4 .which gas is evolved and is collected over  the water as shown in figure?

8.Why is the strength of magnetic field inside a long current carrying straight solenoid same at all point?

9.Define a universal indaicator?

10.Name anyone salt whose  solution has pH more than 7 and one salt whoses solution has pH less  than 7.

11.Why adrenaline is known as emergency hormone ?

Or

Why is car parked in the Sun with windows closed found to be hotter inside than outside.

Or

12.A given length of a wire is doubled on itself and this process is repeated once again.By what factor does the resistance of the wire change?

Or

There are two electric bulbs (i)marked 60W,220V and (I)marked 100W,220V.

Which one of the two has a higher resistance?

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13.Write down the difference between the following pair as indicated within the bracket.Monohybrid and dihybrid cross(phenotypic ratio).

Assertion-Reason Type Questions (Q.nos 14-16)

In in each of the following,statement of assertion is given by the corresponding statement of reason.Of the ,mark the correct answer as

a)If both Assertion and Reason are true and reason is the correct  explanation of Assertion.

b)If both Assertion and Reason are true,but Reason is  not  the correct explanation of Assertion.

c)If Assertion is true ,but reason is false.

d)If Assertion is false,but Reason is true.

14.Assertion:-Maximum concentration of harmful chemicals and pesticides like DDT get accumulated in the human body.

Reason:-Human beings occupy the top most place in any food chain.

15.Assertion:-When focal length of a lens increases ,then it's power decreases.

Reason:-Power of a lens is inversely proportional to focal length of lens.

16.Assertion:-Carbon and it's compound is used as fuel for most application.

Reason:-On combustion of carbon,a large amount of heat and light released.

Or

Assertion:-Generally ,the candle flame is yellow .

Reason:-Candle flame is yellow due to presence of unburnt carbin particles.

Answer Q.nos 17-20 Contain five sub parts each.You are expected to answer any four sub parts in these questions.

17.Read the following and answer any four questions from 17(i) to 17(v).

A few biodegradable and non biodegradable substances are given below :

I-Plastic bags

II)- Paper cups 

III)- Hedge trimmings 

IV)-Aluminium foil

V)-Glass plates 

VI)Vegetable peels 

VII)CFL bulb

VIII)DDT

17(I) Biodegradable waste usually do not pollute the environment .They are considered threat only when 

a)they are present in small amounts.

b)their amount is large 

c)they can't be degraded in nature at right time.

d)Both b and c

17(ii)Which graph shows the most effect of pollution by sewage on the time of oxygen dissolved in river.

a) 

b)

c)

d)

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17.iii) Which organism in the food web below is a producer.

Grass (C)---->Rabbits(D) ---->Eagles (A) and Fleas(B).

a)A

b)C

c)B

d)D

17.iv)The diagram shows a simple version of the energy flow through a food web.

Sunlight------>Plants-------->Animals ---->Decomposers.

What happens to the energy leaving the decomposers?

a) it is lost as heat.

b) it is reflected from the surface of the plants.

c) it is stored as carbohydrates.

d) it is used to power industrial processes.

17v)The diagram show the flow of energy through an ecosystem.

Which arrows represent the smallest amount of energy transferred between organisms ,and the largest amount of energy lost to the ecosystem.

smallest energy transfer- largest atp loss

a)1.                                             3

b)1.                                             4

c)2.                                             3 

d)2 .                                           4

18.Read the following and answer any four question .

There are different types of chemical reaction occurring around us or being carried out for the benefit of mankind,.eg., combination reaction ,decomposition reaction,displacement reaction,percipitation reaction,reduction oxidation (redox) ,photo chemical reaction, etc.

18.i) which of the following reaction is not correct.

a)Zn+CuSO4----->ZnSO4+Cu

b)2Ag+Cu(NO3)2 ---->2AgNO3+Cu

c)Fe+CuSO4--------->FeSO4+Cu

d)Mg+2HCl--------->MgCl2 +H2

18.ii) which type of reaction is involved in white wash of walls.

a)Displacement reaction

b)Redox reaction

c) Combination reaction

d) Decomposition reaction

18.iii) What is the formula of rust

a)Fe3O2.xH2O

b)Fe2xO2.H2O

c)Fe2O3.xH2O

d)Fe2xOx.H2O

18.iv)The acids in column(I) with their source given in cloumn (II).Choose the correct match.

Column I .                                Column.II

A.Lactic acid                         I)Tomato

B.Acetic acid                         II) Lemon 

C.Citric acid                          III)Vinegar

D.Oxalic acid                        IV)Curd

       A         B .                C .               D

a)iv.           ii).               iii).              iv)

b)iv .          i) .               iv) .             iii)

c)iv .         iii)                 i).               ii)

d)v            iii) .              ii) .              i)

18.v)We use  tin- plated instead of nickel-plated because

a) tin is easy to handle

b) tin is less toxic.

c)nickel is very heavy to load.

d)tin is non-poisonous.

19Read the following and answer any four question .

Neha decorates the window of her room using three identical bulbs B1, B2 and  B3 as shown in the figure.All the three bulbs glow, the current of 3A recorded by ammeter A.

19.i) The problem in Connecting the bulbs in  series combination is:

a) the applied voltage is an evenly distributed among all the bulbs.

b) there will be less power consumption.

c) bulb will glow with less brightness.

d) the bulbs get fused easily .

19.ii) Which of the following combination of resistor gives equivalent resistance of 9Ω.

a)

b)

c)

d)

19.iii) In the experiment for finding the equivalent resistance of two resistors resisitors,connected in parallel,the voltmeter has been correctly connected in 

a)

b)

c)

d)

a)Circuit I only 

b)Circuit II only 

c)Both I and III 

d)Both circuits II and IV.

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19.iv) If bulb B2 gets fused ,the total current in the circuit will be 

a)0A

b)1A

c)2A

d)3A

19.v)The following instruments are available in a laboratory:

Milliameter A1 of range 0-300mA and least count 10mA.

Milliameter A2 of range 0-200mA and least count 20mA.

Voltmeter V1 of range 0 - 5V and least count 0.2V

Voltmeter V2 of range 0-3V and least count 0.3V.

Out of following pairs of, which there would be the best choice for carrying out the experiment to determine the equivalent resistance of two resisitors connected in series ?

a)Milliammeter A1 and voltmeter V1 .

b) Milliammeter A2 and voltmeter V2.

c) Milliammeter A1 and voltmeter V2.

d) Milliammeter A2 and voltmeter V1.

20.Read the following and answer any four questions.

The main function of human excretory system is to remove the nitrogenous  waste  such as urea from the body.It include of kidney ,two ureters ,a urinary bladder and urethra . The purpose of making urine is  to filter out waste products from blood. These wastes are removed from the blood by kidneys and are passed  down to urinary bladder by a pair of urine .The urethra further carries the urine out of the body. The phenomena of dischargeing urine to outside is called urine.

20.i)Which of the following is an example of excretion?

a)release of insulin from the pancreas .

b)release of saliva from the salivary glands

c) removal of carbon dioxide from the lungs.

d) removal of faces from the alimentary canal.

20.ii)The diagram given below represents the liver,kidney and some associated blood vessels.identify the vessels from the labelled part A-D in  which the blood will contain the lowest concentration of urea.

a)A

b)B

c)C

d)D 

20.iii) Figure below is representing the dialysis machine for removing nitrogenous waste in patients with kidney failure.

Which substance out of the following in the dialysis fluid should be at a lower concentration that in the blood patient ?

a) glucose and urea 

b)salts and urea 

c) glucose and amino acid

d) glucose and salts.

20.iv)

  Lowest at X .                           Highest at Y

a)glucose .                                    Salts

b)salts .                                         Glucose 

c) urea.                                          Water 

d)water .                                         Urea

 

20.v)How is the working of kidney dialysis machine similar to a healthy kidney.

a) it takes sugar molecules out of the blood.

b) it regulates the concentration of blood.

c) it deaminates amino acid to urea .

d)it removes large molecules from the blood.

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Thank you very much 

By your friend Anuranjan Gadekar

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