OMTEX CLASSES

Maharashtra State Board Class X Science and Technology Board Paper – 2015

Time: 3 hrs Max. Marks: 80

Note:

Use the same answer-sheet for Section A and Section B.

Draw well-labelled diagrams wherever necessary.

All questions are compulsory.

Students should write the answers of questions in sequence.

SECTION A

1. (A) (a) Rewrite the following statements with suitable words in the blanks: [2]

(i) The device used for producing electric current is called _________. (generator)

(ii) _________ the second layer of the atmosphere reaches 48 km above the Earth’s surface. (Stratosphere)

b. Rewrite the following table so as to match the second column with first [2]

Column A	Column B
(i) eosin	(1) losing hydrogen
(ii) oxidation	(2) synthetic indicator
	(3) losing oxygen
	(4) natural indicator

Ans. (i) eosin (2) synthetic indicator

(ii) oxidation (1) losing hydrogen

(c) Give the molecular formula of bleaching powder. [1]

(B) Rewrite the following statements by selecting the correct options : [5]

1. When phenolphthalein is added to NaOH, the colour of the solution will become _________. (colourless)

a. colourless

b. red

c. pink

d. yellow

2. If the potential difference across the ends of a conductor is 220 V and the resistance of the conductor is 44 Ω (ohm), then the current flowing through is _________. (5A)

a. 0.2 A

b. 0.5 A

c. 2 A

d. 5 A

3. 1 A = _________ mA (10³)

a. 10²

b. 10³

c. 10^-3

d. 10^-6

4. The distance between principal focus and optical centre of the lens is _________. (focal length)

a. diameter

b. focal length

c. principal axis

d. optical centre

5. When rays of light are incident on a glass slab then the incident ray and emergent ray are ________ each other. (parallel)

a. perpendicular

b. parallel

c. opposite

d. concurrent

2. Solve any five of the following: [10]

1. Give scientific reason : Danger signals are red in colour.

2. Complete the following reaction, balance it and write the name of the products CuO + HCI → _________ + _________

Ans. CuO + 2HCl → CuCl₂ + H₂O

The name of the products are copper chloride (CuCl₂) (also known as cupric chloride or copper chloride) and water (H₂O).

3. State Newlands‘ Law of Octaves.

4. The velocity of light in a medium is 1.5 × 10⁸ m/s. What is the refractive index of the medium with respect to air, if the velocity in air is 3 x 10⁸ m/s?

Solution : Here, v₁ = 1.5 × 10⁸ m/s and v₂ = 3 x 10⁸ m/s.

We know that, the refractive index with respect to air is

₂η₁ = v₂ ÷ v₁ = (3 x 10⁸ ) ÷ (1.5 × 10⁸) = 2

Thus, the refractive index of the medium with respect to air is 2.

5. Differentiate between resistances in series and parallel.

6. Draw a ray diagram for concave mirror when the object is between centre of curvature and focus.

3. Answer any five of the following : [15]

1. Explain the role of citizen in pollution control.

2. What is a spectrum? Why do we get a spectrum of seven colours when white light is dispersed by a prism?

3. State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?

4. Name the product obtained when Plaster of Paris is mixed with water. State the use of the product. Give two uses of POP.

5. Classify the following elements into metals, non–metals and metalloid: C, Mg, Si, S, Hg, As.

6. Complete the following :

(a)

(b)

(c)

4. Answer any one of the following : [5]

(A) Often when electricity is used we come across electrical fires caused.

Answer the following questions related to the following terms:

1. When does short circuiting take place?

2. What happens to the resistance of the circuit during a short circuit?

3. What happens to the flow of electric current during a short circuit?

3. What is overloading?

4. How can the effects of overloading be avoided?

(B) In a Std. X class out of 40 students 10 students use spectacles, 2 students have positive power and 8 students have negative power of lenses in their spectacles. Answer the following questions:

1. What does the negative power indicate?

2. What does the positive power indicate?

3. Generally which type of spectacles do most of the students use?

4. What defect of eyesight do most of the students suffer from?

5. Give two possible reasons for the above defect.

SECTION B

5. (A) (a) Find the correlation in the given pair and rewrite the answer : [2]

(1) Tinning : Tin : : Galvanizing : _________ (Zinc)

(2) Mammals : _________ : : Amphibia : Fishes (Reptiles)

(b) State True or False : [3]

1. Solar water – heater works on renewable energy system

True