Very Short Questions: Chapter 3 - Metals & Non-Metals, Class 10, Science PDF Download

SHORT QUESTIONS

ANSWER IN SHORT:

1. Which nonmetal is in liquid state ?
   
        ANS : Bromine is the nonmetal in liquid state. 


2. Give an example of a nonmetal which conducts heat and electricity.
   
        ANS : Graphite ( a form of carbon) conducts heat and electricity. 


3. Why are nonmetals electronegative elements ?
   
        ANS : Nonmetals are electronegative elements because they accept electrons and form negatively charged ions. 


4. Which type of oxides do nonmetals form ?
   
        ANS : Nonmetals form either acidic or neutral oxides. 


5. Write formula of carbonic acid.
   
        ANS : The formula of carbonic acid is H₂CO₃. 


6. Give examples of some neutral oxides.
   
        ANS : CO, N₂O, H₂O are examples of neutral oxides. 


7. Why is carbon monoxide a neutral oxide ?
   
        ANS : Carbon monoxide (CO) is a neutral oxide because it forms neither acid nor base with water. 


8. Why do nonmetals not react with dilute acids ?
   
        ANS : Nonmetals do not react with dilute acids because they are not able to displace hydrogen from acids. 


9. Who discovered hydrogen ? When ?
   
        ANS : English chemist Cavendish discovered hydrogen in 1766 AD. 


10. Why is ammonia a very important chemical ?
    
         ANS : Ammonia is a very important chemical because it is used in the preparation of fertilisers, nitric acid, explosives, nylon fibre, etc as well as household cleaners. 


11. Why is ammonia not collected by downward displacement of water ?
    
         ANS : Ammonia is not collected by downward displacement of water because it is highly soluble in water. 


12. What is the full form of PABA ?
    
         ANS : The full form of PABA is Para-Amino Benzoic Acid. 


13. Mention important ores of sulphur.
    
         ANS : Important ores of sulphur are : Zinc blende (ZnS), gypsum (CaSO₄.2H₂O) and copper pyrites (CuFeS₂). 


14. Write electronic configuration of sulphur ?
    
         ANS : The electronic configuration of sulphur is 2,8,6. 


15. When SO₂ is heated with H₂S in the presence of catalyst ______, sulphur is obtained. [Fill up the blank].
    
         ANS : Fe₂O₃. 


16. Mention two crystalline allotropes of sulphur.
    
         ANS : The crystalline allotropes of sulphur are (1) rhombic sulphur (2) monoclinic sulphur. 


17. What is transition temperature ?
    
         ANS : The temperature at which one allotrope of an element changes into another allotrope is called TRANSITION TEMPERATURE of that element. 


18. What is the transition temperature of sulphur ?
    
         ANS : The transition temperature of sulphur is 96°C. 


19. What is the shape of the crystals of rhombic sulphur ?
    
         ANS : The shape of the crystals of rhombic sulphur is octahedral. 


20. What is the shape of the crystals of monoclinic sulphur ? 
    
         ANS : The shape of the crystals of monoclinic sulphur is needle-like. 


21. What is known as the king of chemicals ?
    
         ANS : Sulphuric acid is known as the king of chemicals. 


22. Why is sulphuric acid known as the king of chemicals ?
    
         ANS : Sulphuric acid is known as the king of chemicals because it is used to prepare many important chemical substances like fertilisers, dyes, soap, etc. 


23. Which catalyst is used for conversion of SO₂ into SO₃ in contact chamber ?
    
         ANS : V₂O₅ is used as catalyst for conversion of SO₂ into SO₃ in contact chamber.


24. What is the strength of H₂SO₄ obtained by Contact process ?
    
         ANS : The strength of H₂SO₄ obtained by Contact process is about 100 %.


25. What is charring of sugar ?
    
         ANS : The process in which concentrated sulphuric acid converts sugar to a black mass of carbon (sugar charcoal) by dehydration is called charring of sugar. 


26. Give names of some nonmetallic elements.
    
         ANS : Hydrogen, oxygen, nitrogen, chlorine, bromine, iodine, sulphur, phosphorus, etc. are nonmetallic elements. 


27. Write an equation for the reaction of phosphorus pentoxide with water.
    
         ANS :

    2P₂O_5(g) + 6H₂O_(l) → 4H₃PO_4(aq)



28. Write the equation for the industrial production of hydrogen.
    
         ANS :

    Ni catalyst
    800°C
    30 atm
    CH_4(g) + 2H₂O -----> CO_2(g) + 4H_2(g) 



29. By which method is ammonia gas produced ?
    
         ANS : Ammonia gas is produced by Haber's process. 


30. Which nonmetallic element is obtained by Frasch process ?
    
         ANS : Sulphur is obtained by Frasch process. 


31. Write chemical formula of Oleum (fuming sulphuric acid).
    
         ANS : The chemical formula of fuming sulphuric acid is H₂S₂O₇. 
32. Which crystalline form of sulphur is most stable ?
    
         ANS : Rhombic sulphur is the most stable crystalline form of sulphur. 
33. On which physical property of sulphur is Frasch process based ?
    
         ANS : Frasch process is based on the property of low melting point (388 K) of sulphur. 
34.