CBSE - X
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CBSE X Time allowed: 3 hours; Maximum Marks: 100 |
| General Instructions: | |
| 1) | The question paper comprises of two sections A and B. You are to attempt both sections. |
| 2) | You are advised to attempt all the questions of Section A and Section B separately. |
| 3) | All questions are compulsory. |
| 4) | There is no overall choice. However, internal choice has been provided in some questions. You are to attempt only one option in such questions. |
| 5) | Marks allocated to every question are indicated against it. |
| 6) | Questions number 1-4 in Section A and 17, 18 in Section B are very short answer questions. These are to be answered in one word or one sentence. |
| 7) | Questions number 5-8 in Section A and 19, 20 in Section B are short answer questions. These are to be answered in 30 - 40 words each. |
| 8) | Questions number 9-14 in Section A and 21 - 23 in Section B are also short answer questions.These are to be answered in 40 - 50 words each. |
| 9) | Questions number 15, 16 in Section A and 24 in Section B are long answer questions. These are to be answered in 70 words each. |
Question 1
1. Classify the following reactions into slow and fast reaction:
(i) Reaction between an acid and a base,
(ii) Rusting of iron.
Question 2
2.Give the names of the functional groups
(i)
(ii) 
Question 3
3. What is a Galaxy? (Out of syllabus)
Question 4
4. What is the SI unit of electric potential?(Out of syllabus)
Question 5
5.(b) Choose strong acid and strong base from the following:
Question 6
6. What is Tollen’s reagent? What would you observe on heating Tollen’s reagent with formalin in a test tube? (Out of syllabus)
Question 7
7. Distinguish between polar and equatorial orbits for artificial satellites. Illustrate the two orbits on a diagram.(Out of syllabus)
Question 8
8. An electric iron has a rating of 750 W, 220 V. Calculate
(i) Current passing through it, and
(ii) its resistance, when in use
Question 9
9. Name the raw materials that are required for the manufacture of washing soda by Solvay Process. Describe the chemical reactions involved in the process. (Out of syllabus)
(i) Current passing through it, and
(ii) its resistance, when in use
Question 10
10. What is ‘liquor ammonia’ ? Describe with a diagram,‘Fountain Experiment’ to demonstrate the following properties of ammonia :
(i) high solubility in water.(Out of syllabus)
(ii) its alkaline nature
Question 11
11. Give reasons for the following:
(i) A peculiar smell is observed near the preserved specimens in biology laboratory.(Out of syllabus)
(ii) Methanal undergoes addition reaction with hydrogen cyanide(Out of syllabus)
(iii) Propanone can be used as a nail polish remover.
(iii) Nail polish is an organic compound. Being a good organic solvent propanone (ketone), is used to remove nail polish
Question 12
12. A concave lens has focal length of 20 cm. At what distance from the lens a 5 cm tall object is placed so that it forms an image at 15 cm from the lens? Also, calculate the size of the image formed.
Question 13
13. (a) Why is the solar cooker box covered with a plane glass plate?
(b) Why is energy of water flowing in a river considered to be an indirect form of solar energy?
(c) How is the fission of
nucleus brought about?
Question 14
14. (a)What is meant by ‘Electric Resistance’ of a conductor?
(b) A wire of length L and resistance R is stretched so that its length is doubled and the area of cross-section is halved. How will its:
(i) resistance change?
(ii) resistivity change?
Question 15
15. (a) Name one main ore of Aluminium. Write its formula. Which two main impurities are associated with this ore ?
(b) Describe with chemical equations, the method employed for the enrichment of the above named ore. (Out of syllabus)
Or
(a) Why is sulphuric acid called ‘King of Chemicals’? (Out of syllabus)
(b) Describe the three chemical reactions that take place during the conversion of sulphur dioxide to sulphuric acid in the ‘Contact Process’ (Out of syllabus)
(c) Why should water be never added drop wise to concentrated sulphuric acid?
Question 16
16.Define the term, critical angle. What is meant by ‘total internal reflection’? State two essential conditions for total internal reflection to take place. With the help of a ray diagram, illustrate an application of total internal reflection
Critical angle: The angle of incidence of a ray in a denser medium whose angle of refraction is 
in the rarer medium is known as critical angle.
Total internal reflection: When a ray is travelling from a denser medium to a rarer medium and the angle of incidence is greater than the critical angle, then the refracted ray does not enter the rarer medium but is totally reflected into the denser medium at the surface of separation. This phenomenon is known as total internal reflection.
Conditions for total internal reflection:
a.It occurs when the angle of incidence is greater than the critical angle θc and
b.when the rays of light travel from the denser to rarer medium.
Application of total internal reflection:
The mirage is caused by the total internal reflection of light at layers of air of different densities.
Total internal reflection is used in fiber optics, polarizing prisms etc.
Formation of rainbow:
Rainbow is caused by dispersion of white sun light by tiny water droplets present in the atmosphere. Water droplets act as tiny prisms. They refract and disperse the incident sunlight, then reflect it internally and finally refract it again when it comes out of raindrop. Rainbow is always formed in a direction opposite to that of the appearance of the sun.
Or
(a) What is meant by a ‘magnetic field’?
(b) How is the direction of magnetic field at a point determined?
(c) Describe an activity to demonstrate the direction of the magnetic field generated around a current carrying conductor.
(d) What is the direction of magnetic field at the centre of a current carrying circular loop?
| Section B |