The Central Board of Secondary Education (CBSE) will be conducting the Class 10th board exams from February 21 to March 29, 2019. The last date for submission of online application forms is October 2018.
Students can start their preparation for the exams by solving sample papers. Here we are providing the Last Year Science Board Question Paper for Class 10th 2019 – SET – 3. This paper will help students to score good marks in the exams.
Are you searching cbse previous year question papers class 10 science (set – 3) in text format. Your all problems, solution here go ahead.
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Science Board Question Paper for Class 10th 2019
SET – 3
1 – Why does the cord of an electric oven not glow while its heating element does ?
2 – Although coal and petroleum are produced by the degradation of biomass, yet we need to conserve these resources. Why ?
3 – What is atmospheric refraction ? List two phenomena which can be explained on the basis of atmospheric refraction.
4 – Name a metal of medium reactivity and write three main steps in the extraction of this metal from its sulphide ore.
5 – List two chemical properties on the basis of which ethanol and ethanoic acid may be differentiated and explain how.
Unsaturated hydrocarbons contain multiple bonds between two carbon atoms and these compounds show addition reactions. Out of saturated and unsaturated carbon compounds, which compounds are more reactive ? Write a test to distinguish ethane from ethene.
6 – What happens to a beam of white light when it gets refracted through a glass prism ? Which colour deviates the most and the least after refraction through a prism ? What is likely to happen if a second identical prism is placed in an inverted position with respect to the first prism ?Justify your answer.
A student needs spectacles of power – 0·5 D for the correction of his vision.
(i) Name the defect in vision the student is suffering from.
(ii) Find the nature and focal length of the corrective lens.
(iii) List two causes of this defect.
7 – Define a food chain. Design a terrestrial food chain of four trophic levels. If a pollutant enters at the producer level, the organisms of which trophic level will have the maximum concentration of the pollutant in their bodies ? What is this phenomenon called ?
8 – What are solar cells ? Explain the structure of solar panel. List two principal advantages associated with solar cells.
9 – During the reaction of some metals with dilute hydrochloric acid, the following observations were made by a student :
(a) Silver does not show any change.
(b) Some bubbles of a gas are seen when lead is reacted with the acid.
(c) The reaction of sodium is found to be highly explosive.
(d) The temperature of the reaction mixture rises when aluminium is added to the acid. Explain these observations giving appropriate reason.
10 – Given below are the steps for the extraction of copper from its ore. Write the chemical equation of the reactions involved in each case.
(i) Roasting of copper (I) sulphide
(ii) Reduction of copper (I) oxide from copper (I) sulphide
(iii) Electrolytic refining
11 – (a) While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid ?
(b) Dry hydrogen chloride gas does not change the colour of dry litmus paper. Why ?
How is sodium hydroxide manufactured in industries ? Name the process. In this process a gas X is formed as by-product. This gas reacts with lime water to give a compound Y, which is used as a bleaching agent in the chemical industry. Identify X and Y and write the chemical equation of the reactions involved.
12 – What is a homologous series of carbon compounds ? Give an example and list its three characteristics.
13 – What is transpiration ? List its two functions.
(a) What is translocation ? Why is it essential for plants ?
(b) Where do the substances in plants reach as a result of translocation ?
14 – List in tabular form three distinguishing features between autotrophic nutrition and heterotrophic nutrition.
15 – (a) Budding, fragmentation and regeneration, all are considered as asexual mode of reproduction. Why ?
(b) With the help of neat diagrams, explain the process of regeneration in Planaria.
16 – A 6 cm tall object is placed perpendicular to the principal axis of a concave mirror of focal length 30 cm. The distance of the object from the mirror is 45 cm. Use mirror formula to determine the position, nature and size of the image formed. Also draw labelled ray diagram to show the image formation in this case.
An object 6 cm in size is placed at 50 cm in front of a convex lens of focal length 30 cm. At what distance from the lens should a screen be placed in order to obtain a sharp image of the object ? Find the nature and size of the image. Also draw labelled ray diagram to show the image formation in this case.
17 – Draw the pattern of magnetic field lines produced around a current carrying straight conductor passing perpendicularly through a horizontal cardboard. State and apply right-hand thumb rule to mark the direction of the field lines.
How will the strength of the magnetic field change when the point where magnetic field is to be determined is moved away from the straight conductor ? Give reason to justify your answer.
18 – (a) How will you infer with the help of an experiment that the same current flows through every part of a circuit containing three resistors in series connected to a battery ?
Consider the given circuit and find the current flowing in the circuit and potential difference across the 15 resistor when the circuit is closed.
(a) Three resistors R1, R2 and R3 are connected in parallel and the combination is connected to a battery, ammeter, voltmeter and key. Draw suitable circuit diagram and obtain an expression for the equivalent resistance of the combination of the resistors.
(b) Calculate the equivalent resistance of the following network.
19 – (a) List any three observations which posed a challenge to Mendeleev’s Periodic Law.
(b) How does the metallic character of elements vary on moving from
(i) left to right in a period,
(ii) from top to bottom in a group of the Modern Periodic Table ? Give reason for your answer.
The electrons in the atoms of four elements A, B, C and D are distributed in three shells having 1, 3, 5 and 7 electrons respectively in their outermost shells. Write the group numbers in which these elements are placed in the Modern Periodic Table. Write the electronic configuration of the atoms of B and D and the molecular formula of the compound formed when B and D combine.
20 – What is sexual reproduction ? Explain how this mode of reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution ?
21 – (a) Why is the use of iodised salt advisable ? Name the disease caused due to deficiency of iodine in our diet and state its one symptom.
(b) How do nerve impulses travel in the body ? Explain.
What is hydrotropism ? Design an experiment to demonstrate this phenomenon.
22 – The current flowing through a resistor connected in a circuit and the potential difference developed across its ends are as shown in the diagram by milliammeter and voltmeter readings respectively :
(a) What are the least counts of these meters ?
(b) What is the resistance of the resistor ?
23 – Draw the path of a ray of light when it enters one of the faces of a glass slab at an angle of nearly 45. Label on it (i) angle of refraction, (ii) angle of emergence and (iii) lateral displacement.
A student traces the path of a ray of light through a glass prism as shown in the diagram, but leaves it incomplete and unlabelled. Redraw and complete the diagram. Also label on it i, e, r and D.
24 – What is observed when a pinch of sodium hydrogen carbonate is added to 2 mL of acetic acid taken in a test tube ? Write chemical equation for the reaction involved in this case.
25 – A teacher provided acetic acid, water, lemon juice, aqueous solution of sodium hydrogen carbonate and sodium hydroxide to students in the school laboratory to determine the pH values of these substances using pH papers. One of the students reported the pH values of the given substances as 3, 12, 4, 8 and 14 respectively. Which one of these values is not correct ? Write its correct value stating the reason.
What would a student report nearly after 30 minutes of placing duly cleaned strips of aluminium, copper, iron and zinc in freshly prepared iron sulphate solution taken in four beakers ?
26 – List four precautions which a student should observe while preparing a temporary mount of a leaf peel to show stomata in his school laboratory.
27 – List in proper sequence four steps of obtaining germinating dicot seeds.
After examining a prepared slide under the high power of a compound microscope, a student concludes that the given slide shows the various stages of binary fission in a unicellular organism. Write two observations on the basis of which such a conclusion may be drawn.
The article header titled Last Year Science Board Question Paper for Class 10th 2019 – SET – 3 would discuss the question paper for the class 10th science board examination from last year. The paper would be from SET 3 and would consist of 8 sentences.
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