Subject

Science

Class

CBSE Class 10

Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Read the following statements:                                                                        

 

I. When a red litmus paper is dipped into reaction mixture of a saponification reaction, it turns blue and the reaction is exothermic.

II. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its color does not change and the reaction is exothermic.

III. When a red litmus paper is dipped into reaction mixture of a saponification reaction, its color does not change and the reaction is endothermic.

IV. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its color does not change and the reaction is endothermic.

Which of the above statements are correct?

  • I, and II

  • II and III

  • III and IV

  • I and IV


A.

I, and II

Soap solution is basic in nature and saponification is an exothermic reaction. Therefore, the red litmus paper is turned to blue.

Color of the blue litmus paper does not change when it is dipped in the soap solution. 

1949 Views

2.

A student focused the image of a distant object using a device ‘X’ on a white screen ‘S’ as shown in the figure. If the distance of the screen from the device is 40 cm, select the correct statement about the device. 

  • The device X is a convex lens of focal length 20 cm.

  • The device X is a concave mirror of focal length 40 cm.

  • The device X is a convex mirror of radius of curvature 40 cm.

  • The device X is a convex lens of focal length 40 cm.


D.

The device X is a convex lens of focal length 40 cm.

3110 Views

3.

A student prepared 20% sodium hydroxide solution in a beaker containing water. The observations noted by him are given below.                                                         

I. Sodium hydroxide is in the form of pellets.

II. It dissolves in water readily.

III. The beaker appears cold when touched from outside.

IV. The red litmus paper turns blue when dipped into the solution.

The correct observations are:

  • I, II, and III

  • II, III and IV

  • III, IV and I

  • I, II and IV


D.

I, II and IV

Sodium hydroxide is in the form of pallets and it readily dissolves in water to form a solution. Since, it is basic in nature, NaOH  turns red litmus paper blue.

1806 Views

4.

A student takes 2 mL acetic acid in a dry test tube and adds a pinch of sodium hydrogen carbonate to it. He makes the following observations:                                       

I. A colorless and odorless gas evolves with a brisk effervescence.

II. The gas turns lime water milky when passed through it.

III. The gas burns with an explosion when a burning splinter is brought near it.

IV. The gas extinguishes the burning splinter that is brought near it.

The correct observations are:

  • I, II, and III

  • II, III and IV

  • III, IV and I

  • IV, I and II


D.

IV, I and II

Reason: When 2 mL acetic acid is taken in a dry test tube and a pinch of sodium hydrogen carbonate is added to it, a colorless and odorless gas evolves with a brisk effervescence which is CO2.  

stack CH subscript 3 COOH with acetic space acid below space plus space stack straight N subscript straight a HCO subscript 3 with Sodium space hydrogen space carbonate below space rightwards arrow stack C H subscript 3 C O O N a with S o d i u m space s c e t a t e below space plus H subscript 2 O space plus space stack C O subscript 2 with c a r b o n space d i o x i d e below

When CO2 is passed through lime water it turns lime water turns milky.
stack Ca left parenthesis OH subscript 2 right parenthesis end subscript space left parenthesis aq right parenthesis with lime space water below space plus space C O subscript 2 space left parenthesis g right parenthesis space rightwards arrow space end subscript stack C a C O subscript italic 3 italic space italic left parenthesis s italic right parenthesis italic space end subscript with w h i t e italic space p p t below plus space H subscript 2 O


CO2 also extinguishes the burning splinter when it is brought near it.

4776 Views

5.

Select from the following the best set-up for tracing the path of a ray of light through a rectangular glass slabs:


A.

The incoming light should not fall perpendicularly as the light will emerge straight and refraction cannot be traced. The light rays should not be very close or far from the normal as the emergent rays are difficult to trace. 

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6.

Hard water required for an experiment is not available in a school laboratory. However, following salts are available in the laboratory. Select the salts which may be dissolved in water to make it hard for the experiment.                                                            

(1)

Calcium Sulphate

(2)

Sodium Sulphate

(3)

Calcium Chloride

(4)

Potassium Sulphate

(5)

Sodium Hydrogen Carbonate

(6)

Magnesium Chloride

  • 1, 2 and 4

  • 1, 3 and 6

  • 3, 5 and 6

  • 2, 4 and 5


B.

1, 3 and 6

Hard water contains Ca2+ and Mg2+ ions. So, the salts that can be added to water to make it hard are calcium sulphate, calcium chloride and magnesium chloride. 

1830 Views

7.

After tracing the path of rays of light through a glass slab for three different angles of incidence, a student measured the corresponding values angle of refraction r and angle of emergence e and recorded them in the table given below: 


S. No.

i

r

e

I

30°

20o

31o

II

40o

25o

40o

III

50o

31o

49o


The correct observations are:

A) 
B)
C) I and III
D) I, II and III

  • I and II

  •  II and III

  • I and III

  • I, II and III


D.

I, II and III

For light rays passing through a glass slab, the following conditions should hold true:

  1. angle straight i space almost equal to space angle straight e space and space angle straight r space less than angle straight i 
  2. Also, Angle of refraction increases with increase in incident angle.

The given observations satisfy both these conditions.

1185 Views

8.

In an experiment to study the properties of acetic acid a student takes about 2 mL of acetic acid in a dry test tube. He adds about 2 mL of water to it and shakes the test tube well. He is likely to observe that:      

  •  the acetic acid dissolves readily in water

  • the solution becomes light orange

  • water floats over the surface of acetic acid

  • acetic acid floats over the surface of water


A.

 the acetic acid dissolves readily in water

The acetic acid dissolves readily in water.

556 Views

9.

In an experiment to trace the path of a ray of light through a glass prism for different values of angle of incidence a student would find that the emergent ray:

  • is parallel to the incident ray

  • Perpendicular to the incident ray

  • is parallel to the refracted ray

  • bends at an angle to the direction of incident ray


D.

bends at an angle to the direction of incident ray

The light ray gets refracted two times at different angles. So, emergent ray bends at an angle towards the direction of incident ray.

600 Views

10.

A student obtained a sharp image of a burning candle, placed at the farther end of a laboratory table, on a screen using a concave mirror. For getting better value of focal length of the mirror, the subject teacher suggested him for focusing a well illuminated distant object. What should the student do?

  • He should move the mirror away from the screen.

  • He should move the mirror slightly towards the screen.

  • He should move the mirror as well as the screen towards the newly selected object.

  • He should move only the screen towards the newly selected object.


B.

He should move the mirror slightly towards the screen.

On increasing the image distance, the object distance decreases. So, the mirror-screen distance should be decreased. That is, the mirror should be moved towards the screen.

1441 Views