View note:CBSE-class-10-Science-2018



Questions of this subject!.

QuestionLikes!Dislikes!Answers!
1)A Mendelian experiment consisted of breeding pea plants bearing violet flowers with pea plants bearing white flowers. What will be the result in F1 progeny ?

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2)Write the energy conversion that takes place in a hydropower plant.

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3)A compound ‘X’ on heating with excess conc. sulphuric acid at 443 K gives an unsaturated compound ‘Y’. ‘X’ also reacts with sodium metal to evolve a colourless gas ‘Z’. Identify ‘X’, ‘Y’ and ‘Z’. Write the equation of the chemical reaction of formation of ‘Y’ and also write the role of sulphuric acid in the reaction.

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4)(a) Name one gustatory receptor and one olfactory receptor present in human beings.

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5)If the image formed by a spherical mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it ? Draw a labelled ray diagram to support your answer.

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6)Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactants. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity.

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7)2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the contents are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid.

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8)The pH of a salt used to make tasty and crispy pakoras is 14. Identify the salt and write a chemical equation for its formation. List its two uses.

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9)Why are most carbon compounds poor conductors of electricity ?

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10)Write the name and structure of a saturated compound in which the carbon atoms are arranged in a ring. Give the number of single bonds present in this compound.

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11)Name the hormones secreted by the following endocrine glands and specify one function of each : (a) Thyroid (b) Pituitary (c) Pancreas

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12)Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival – the one reproducing asexually or the one reproducing sexually ? Give reason to justify your answer.

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13)State the laws of refraction of light. Explain the term ‘absolute refractive index of a medium’ and write an expression to relate it with the speed of light in vacuum.

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14)What is meant by power of a lens ? Write its SI unit. A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens.

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15)Show how would you join three resistors, each of resistance 9  so that the equivalent resistance of the combination is (i) 13.5  (ii) 6  ?

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16)Write Joule’s law of heating.

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17)Two lamps, one rated 100 W; 220 V, and the other 60 W; 220 V, are connected in parallel to electric mains supply. Find the current drawn by two bulbs from the line, if the supply voltage is 220 V.

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18)List the factors on which the resistance of a conductor in the shape of a wire depends.

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19)Why are metals good conductors of electricity whereas glass is a bad conductor of electricity ? Give reason.

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20)Why are alloys commonly used in electrical heating devices ? Give reason.

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21)What is a dam ? Why do we seek to build large dams ? While building large dams, which three main problems should particularly be addressed to maintain peace among local people ? Mention them.

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22)Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores.

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23)How is copper extracted from its sulphide ore ? Explain the various steps supported by chemical equations. Draw labelled diagram for the electrolytic refining of copper.

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24)The modern periodic table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts.

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25)Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass.

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26)Write the principle of working of an electric motor.

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27)State Fleming’s left hand rule.

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28)Why does the sun appear reddish early in the morning ? Will this phenomenon be observed by an astronaut on the Moon ? Give reason to justify your answer.

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29)Write the function of each of the following parts of human eye : (i) Cornea (ii) Iris (iii) Crystalline lens (iv) Ciliary muscles

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30)Why do stars twinkle ? Explain.

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31)A student is unable to see clearly the words written on the black board placed at a distance of approximately 3 m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it.

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32)Describe in brief the structure and function of placenta.

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33)Write the function of following parts in human female reproductive system : (i) Ovary (ii) Oviduct (iii) Uterus

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34)Name the basic filtration unit present in the kidney.

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35)Define excretion.

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36)Write one structural difference between the composition of artery and veins.

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37)Write the function of valves present in between atria and ventricles.

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38)Trace the movement of oxygenated blood in the body.

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39)Mention any two components of blood.

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40)State Modern periodic law.

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41)An object of height 4.0 cm is placed at a distance of 30 cm from the optical centre ‘O’ of a convex lens of focal length 20 cm. Draw a ray diagram to find the position and size of the image formed. Mark optical centre ‘O’ and principal focus ‘F’ on the diagram. Also find the approximate ratio of size of the image to the size of the object.

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42)A student is viewing under a microscope a permanent slide showing various stages of asexual reproduction by budding in yeast. Draw diagrams of what he observes. (in proper sequence)

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43)List the steps of preparation of temporary mount of a leaf peel to observe stomata.

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44)Name the process by which an amoeba reproduces. Draw the various stages of its reproduction in a proper sequence.

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45)Explain the function of the following parts of an electric motor. (i) Armature (ii) Brushes (iii) Split ring

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46)(class 12 Computer science CBSE 2018) What possible output(s) are expected to be displayed on screen at the time of execution of the program from the following code ? Also specify the maximum values that can be assigned to each of the variables BEGIN and LAST.

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