Practice paper 4
Class 10th
1) One half of convex lens is covered with a black paper.Will this lens produce a complete image of the object?Show
it by using ray diagram.
2) a. Draw a ray diagram to show the formation of a rainbow and mark the points where dispersion and internal
reflection occurs.
b. What is the far point of the human eye with normal vision?
3) Give reason for the following:-
a. Aqueous solution of glucose and acetone are not considered to be acidic though they contain hydrogen
b. Carbon dioxide is an acidic gas
c. Baking soda is added to the dough for making bhaturas.
4) Copper sulphate crystals are heated gently in a dry boiling tube .Write two observations for this activity.Write the
chemical equation for the reaction taking place.
5) a. How is mercury extracted from its sulphide ore? Explain the various steps supported by chemical equations.
b. Name this ore and the method used for concentration of this ore.
6) Give reason:-
a. Corrosion of iron is undesirable but that of aluminium is preferred.
b. Metals like sodium and magnesium cannot be obtained from their oxides by heating with carbon.
7) In the given set up zinc granules were added to dilute sulphuric acid .A gas was produced which was passed
though soap solution.A lighted matchstick was brought near the
bubbles to test the gas
a. Whyn is the gas passed through soap solution?
b. What will you observe when the lighted matchstick is brought near
the bubbles?
c. Which gas will be produced if in this experiment zinc was added to
hot sodium hydroxide solution?
8) Magnesium ribbons are dipped in two beakers A and B containing copper sulphate solution and iron sulphate
solution respectively.What will you observe in the two test tubes?Explain your observations.
9) Consider the following salts:
Na2CO3, NaCl, NH4Cl, CH3COONa. Which of these salts will give
i) Acidic solution ii) Neutral solution iii) Basic solution
10) On heating copper powder in air the surface of copper powder becomes coated with black CuO.How can this
black coating be converted into brown copper?Write chemical equation for the reaction that occurs during the
colour change.
11) Complete and balance the following chemical equations:-
i) K2CO3 +HCl—---------> ii) CuO +HCl—----------> iii) Fe +HCl—------------>
12) A copper wire has cross sectional area 4x10 m2 and resistivity of 1.6x10-8 ohm metre.Calculate the length of
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the wire to make its resistance 10 ohms.How much does the resistance change, if the diameter is doubled?
13) In an electric field the work done in bringing a 2 coulomb charge from infinity to a point A is 10 joules and in
bringing the same charge to some other point B is 20 joules.Find the potential difference between two points A and
B .What would be the work done if the same charge is brought directly from A to B?
14) An ore ,on heating in air,gives sulphur dioxide gas.Name the method in each metallurgical step,that will be
required to extract this metal from its ore.
15) The pH value of six solutions A,B,C,D,E and F are 0,11,6,7,13 and 8 respectively.Which of these solutions is
i)Weak acid ii) weak base iii) Strong acid iv) Strong base v) Neutral.
Arrange the solutions A,B,C,D,E and F in decreasing order of hydrogen ion concentration.
