Q43. There are three materials X, Y and Z. X and Z are hard and shiny, but Y is dull and not very hard. Identify the metals and non-metals from X, Y and Z.

 

Q44. Why wires are made of aluminum and copper and not of carbon and sulphur?

 

Q45. How phosphorus is stored?

Or

Why is phosphorous stored in water?

Or

What will happen if phosphorus is kept in open air?

Or

Why do we store white phosphorus in water?

 

Q46. Why are wooden or plastic handles used for cooking utensils?

Or

Why can’t we hold a hot metallic pan without a plastic or wooden handle without getting hurt?

 

Q47. Why there is difference in sound on dropping a metal coin and a piece of coal?

 

Q48. What does the ‘pop’ sound indicate in a reaction?

 

Q49. What is an element? Give example.

 

Q50. “The atom of an element remains unaffected by physical changes in the element.” Explain the statement with the help of example.

 

Q51. How are elements classified?

 

Q52. Why are electric wire made of copper?

Or

Why are copper metal wires used to conduct electricity?

 

Q53. Why can't copper displace zinc from its salt solution?

Or

Copper cannot displace zinc from its salt solution. Give reason.

 

Q54. Can you store lemon pickle in an aluminium utensil? Explain.

 

Q55. Complete the following reactions of iron and magnesium with oxygen.

Iron (Fe) + Oxygen (O2) + Water (H2O) → ?

Magnesium (Mg) + Oxygen (O2) → ?

 

Q56. Explain reaction between sulphur and oxygen. What is the nature of its oxide formed?

 

Q57. Can copper displace iron from iron sulphate solution? Give reason.

Or

Why copper cannot displace iron from iron sulphate solution?

 

Last modified: Tuesday, 14 May 2019, 9:19 PM