MCQs Olympiad NSO Science

1. 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)
2.   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)
3.   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)
4.   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)
5.   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)
6.   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)
7. A metal is used for making electrical wires and cables. Its ore is concentrated by froth floatation method. If this metal is left in the air for some time, it gets corroded by developing a greenish deposit on it. Which metal are we talking about ?
(a) Zn                                                              
(b) Fe
(c) Cu                                                            
(d) Sn                                                   
Ans (c)
8.   What is common among the ores of different metals ?
(a) They are all oxides                                              
(b) They are all sulphides
(c) They are all minerals                                         
(d) Both (a) & (c)                             
Ans (c)
9.   Few statements about the metals given below and matched with the metals. Mark the incorrect match.
(a) A metal used in joining electric wires - Magnesium
(b) A metal whose oxide is amphoteric - Zinc
(c) A metal unreactive towards oxygen and dilute acids - Gold
(d) A metal extracted by using electrolytic reduction – Aluminium                                
Ans (a)
10.   10 mL of freshly prepared iron sulphate was taken in four test tubes each. Strips of copper, iron, zinc and aluminium were introduced in these tubes. Which of the metals will show reaction ?
(a) Copper and Zinc                                            
(b) Aluminium and copper
(c) Iron and aluminium                          
(d) Zinc and aluminium                                 
Ans (d)
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