Question Paper Olmpiad NSO Scinece

1. A student wrote three statements about rancidity :
I.   When fats and oils are reduced, they become rancid.
II.  Chips manufacturers usually flush chips bags with oxygen to prevent rancidity.
III. Rancidity is prevented by adding substances called antioxidants to food.
Choose the correct statement(s) :
(a) I                                                                                       
(b) II and III
(c) III                                                                                     
(d) I, II and III                                                                    
Ans (c)
2.  Metal X is found in earth’s crust. This metal forms a reddish brown powder when exposed to moist air. When a blue coloured solution Y is stored in a container made of X, the solution turns green and reddish brown metal Z is deposited on the container. X, Y and Z respectively are
(a) Cu, CuSO4, Fe                                                             
(b) Zn, ZnSO4, Fe
(c) Fe, CuSO4, Cu                                                             
(d) Cu, FeSO4, Fe                                                             
Ans (c)
3. A student added dilutr HCL to a test tube containing zinc granules. Which of the
following observations are correct ?
I.   Zinc surface became dull and black.
II.  A gas was evolved which burnt with a pop sound.
III. The solution remained colourless.
(a) I and II                                                                           
(b) I and III
(c) II and III                                                                        
(d) I, II and III                                                                    
Ans (d)
4. Which of the following reactions are exothermic in nature ?
(i) Evaporation of water                               (ii) Dissolution of sodium hydroxide in water
(iii) Dilution of sulphuric acid                       (iv) Dissolution of ammonium chloride in water
(v) Combustion of methane gas                                                                               
(a) (i), (iv) and (v)                                                            
(b) (ii), (iii) and (v)
(c) (i), (ii) and (iv)                                                            
(d) (i), (iii) and (iv)                                                           
Ans (b)
5. A teacher gave two test tubes to the students, one containing water and the other containing sodium hydroxide. She asked them to identify the test tube containing sodium hydroxide solution. Which one of the following can be used for the identification ?
(a) Blue litmus                                                                                  
(b) Red litmus
(c) Sodium carbonate solution                                                  
(d) Dilute hydrochloric acid                         
Ans (b)
6.  The pH of a solution is 7. How can you increase its pH ?
(a) By adding a small amount of acid
(b) By adding a small amount of base
(c) By adding a small amount of salt
(d) By passing carbon dioxide gas through it                                                                                                       
Ans (b)
7. The oxide of a metal M is water soluble. When a blue litmus strip was dipped in this solution, it did not undergo any change in colour, but it changed the colour of phenolphthalein. What is the nature of the oxide ?
(a) Acidic                                                                                             
(b) Basic
(c) Neutral                                                                                         
(d) Amphoteric                                                
Ans (b)
8. When the stopper of a bottle containing colourless liquid was removed, the bottle gave a smell like that of vinegar. The liquid in the bottle could be :
(a) Hydrochloric acid solution                                                     
(b) Sodium hydroxide solution
(c) Saturated sodium bicarbonate solution                          
(d) Acetic acid solution                                 
Ans (c)
9. The pH of three solutions X, Y and Z is 6, 4 and 8 respectively. Which of the following is the correct order of acidic strength ?
(a) X > Y > Z                                                                                        
(b) Z > Y > X
(c) Y > X > Z                                                                                        
(d) Z > X > Y                                                       
Ans (c)
10. Acetic acid was added to a solid X kept in a test tube. A colourless and odourless gas was evolved. The gas was passed through lime water which turned milky. It was concluded that :
(a) Solid X is sodium hydroxide and the gas evolved is H2
(b) Solid X is sodium bicarbonate and the gas evolved is CO2
(c) Solid X is sodium acetate and the gas evolved is CO2
(d) Solid X is sodium chloride and the gas evolved is H2                                                                                  
Ans (b)
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