Sunday, September 17, 2017

CBSE Class 10 -Chemistry - Metals and Non-Metals (Short Q and A)(#cbseNotes)

Metals and Non-Metals (Short Q and A)

CBSE Class 10 -Chemistry -  Metals and Non-Metals (Short Q and A)(#cbseNotes)

Q1: Define Element.

Answer: An element is a pure substance which is made up of same kind of atom which differs from their physical and chemical properties.

Q2: How many elements are known so far? How many of them are naturally occurring?

Answer: 118 under which 92 are naturally occurring.

Q3: Give examples of the most abundant elements.

Answer: Aluminium ( the most) and Iron

Q4: Which is the most abundant non-metal?

Answer: Oxygen (O)

Q5: Give examples of the least reactive metals.

• Gold
• Silver
• Platinum

Q6: Name three the most reactive metals metals.

• Sodium
• Potassium
• Calcium

Q7: What is a mineral?

Answer: A mineral is a naturally occurring inorganic substance found deep inside the earth surface.

Q8: What is an ore?

Answer: Ore is a mineral from which one or more metals can be extracted economically and profitably.

Q9: Give two examples ore of iron?

Answer: Hematite (Fe₂O₃) and Magnetite(Fe₃O₄)

Q10: Give two examples of ore of aluminium?

Answer: Bauxite (Al₂O₃.H₂O) and Cryolite (Na₃AlF₆)

Q11: Name two metals which can be cut by a knife.

Answer: Na & K are soft and can be easily cut by knife.

Q12: Define ductility.

Answer: Ductility is defined as the property of metals to be drawn into thin wires.

Q13: Give examples of the most ductile metals.

Answer: Gold and silver

Q14: Define malleability.

Answer: Malleability is defined as the property of metals to be drawn into thin sheets on hammering.

Q15: Give two examples of the most malleable metals.

Answer: Gold and Silver

Q16: Give an example of non-metal which is a good conductor of heat and electricity.

Answer: Graphite

Q17: Give examples of metals which are poor conductors of electricity.

Answer: Lead and mercury are bad conductors.

Q18: What are metalloids? Give examples of metalloids.

Answer: There are some metals which show some properties of a metals and non metals. Such elements are called metalloids.
e.g. Germanium, Silicon, Arsenic.

Q19: What are noble metals?

Answer: Those metals that have least reactivity and do not react with air, water, acids and bases are referred to as noble metals.
For example: Gold, Platinum

Q20: Name the metal added to gold to make it hard.

Answer: Copper

Q21: What is rusting?

Answer: It is the type of corrosion which occurs due to the formation of brown colored layer of iron oxide called rust formed on iron when exposed to moist air.

Q22: Give chemical formular of iron rust.

Answer: Fe₂O₃.XH₂O

Q23: Name five ways to prevent rusting.

Oiling and greasing

Q24: Are metals electropositive or elctronegative? State reason also.

Answer: Metals are elements that have a tendency to lose electrons and form cations. They have electropositive character.

Q25: Are non-metals electropositive or elctronegative? State reason also.

Answer: Non-metals are elements that have a tendency to gain electrons and form anions. They have electro-negative character.

Q26: What is Gangue?

Answer: The impurity of soil, sand and rocky material present in the ore is called as gangue.

Q27: Define Calcination.

Answer: The process of converting carbonate ore into oxides by heating strongly in limited supply of air is called as calcination.

Q28: What is roasting?

Answer: The process of converting sulphide ore into oxide by heating strongly in presence of excess air is called roasting.

Q29: What is electrolytic refining?

Answer: The process of purifying impure metals is called as refining or electrolytic refining.

Q30: Define galvanising.

Answer: It is a process of giving a thin coating of zinc on iron or steel to protect it from corrosion.

Q31: Give an example of amphoteric oxide.

Answer: Aluminium Oxide

Q32: Sodium and chlorine are poisonous substances but sodium chloride is edible. State reason.

Answer: Sodium chloride is a compound of sodium and chlorine. It is a new product, neutral and chemically different from its consituent elemets. Hence it is edible.

Q33: Why does NaCl conduct electricity in moten state or in aqueous state?

Answer: In aqueous solution, sodium chloride splits into sodium ions (Na⁺) and chloride (Cl⁻). These ions are free to move in the solution and conducts electricity.

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