CBSE Guess Paper 2010

Science

Class - X

Q1. How is concentration of OH^- ions affected when excess of base is dissolved in water? 1

Q2. Name the compound which is used to remove hardness of water. 1

Q3. Which of the following give addition reaction and why?     1

CH4; C2H2; C3H8; C4H10

Q4. What is meant by the power of accommodation of human eye?    1

Q5. Why does the color of ferrous sulphate change when a piece of zinc is placed in it?      1

Q6. Why do HCl and HNO₃ show acidic behaviour in water while ethanol and glucose do not yet they contain hydrogen in them?      1

Q7. How does the electronic configuration of an atom relate to its position in the modern periodic table?      2

Q8. A baker found that the cake prepared by him is hard and small in size. Which ingredient has he forgotten to add? Give reason.       2

Q9. Why do the faces of persons sitting opposite to you around a camp fire appear to shimmer?            2

Q10. (a) How is the concentration of hydronium ion affected, when an acid is diluted with water?

(b) Why should sour substances not kept in brass and copper vessels?   2

Q11. (a) Explain what corrosion of iron means?

(b) Explain, Why an aqueous solution of ammonium chloride is acidic in nature.     2

Q12. (a) How is corrosion of iron prevented by coating it with a layer of oil?

(b) In which situation do we use Fleming.s right hand rule?

(c) Why is it that aluminium which is more reactive than iron does not corrode like iron?     3

Q13. (a) Two conducting wires of the same material and of the same lengths and equal diameters are first connected in series and the parallel in an electrical circuit. Find the ratio of heat produced in series and parallel combinations.

(b) One half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.      3

Q14. What is water of crystallization? Which two features of crystals generally depend on it?      

                                              OR

What will happen if heating is not controlled in preparing of plaster of Paris? Give equation.      2

Q15. (a) How do Mendel.s experiments show that traits are inherited independently?

(b) A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits . blood group A or O . is dominant? Why or why not?      3

                                          OR

Describe the structure and functioning of nephron along with a well labeled diagram.