Extra Questions for Class 10th: Ch 3 Metals and Non-Metals Science

Extra Questions for Class 10th: Ch 3 Metals and Non-Metals (Science) Important Questions Answer Included

Very Short Answer Questions (VSAQs): 1 Mark

Q1. Why does Calcium floats in water?
Answer
Calcium floats in water due to hydrogen gas, evolved hydrogen gas got stricken to the calcium surface, hydrogen being lighter gas than water, make calcium float.

Q2. Name two metals which can evolve hydrogen gas by reacting with very dilute nitric acid?
Answer
Magnesium and Manganese.

Q3. How graphite is different any other non-metals?
Answer
Graphite conducts electricity.

Q4. Name the type of bond formed, when metals reacts with other metallic salts?
Answer
Ionic bond

Q5. What is the name of alloys of mercury?
Answer
Amalgam

Short Answer Questions-I (SAQs-I): 2 Marks

Q1. What is thermite reaction? What is its application?
Answer
Iron is displaced from its oxide using Alumunium. The reaction is highly exothermic.
Fe2O3 (s)+2Al(s)→Fe(l)+Al2O3 (s)+Heat
The heat obtained is so high that iron is obtained in molten form.
This reaction is used  to join railway tracks or cracked machine parts.

Q2. Why ionic compounds are having higher melting and boiling point?
Answer
Ionic compounds are having higher melting and boiling point because they are bonded together by strong electrostatic force of attraction. Their particles are strongly bonded together. It is difficult to break their strong force of attraction. So, it requires a very high energy and hence temperature to increase the inter molecular space.

Q3. Write balanced chemical equations for
ZnCO3 is heated in absence of Oxygen
Zinc Oxide reduced to zinc by reducing by coke
Answer
(i) 
(ii) ZnO+C→CO+Zn

Q5. A metal X left in moist air for a longer time, loses its shiny brown surface and gains a green coat. Why has this happened ? Name and give the chemical formula of this given coloured compound and identify the metal. List two ways to prevent this process. 
Answer
The metal has corroded because of being exposed to moist air.  Green compound is basic copper carbonate [CuCO3.Cu(OH)2] . The metal is copper. 
Two ways to prevent this process : Painting, Greasing, Oiling, Galvanizing.

Short Answer Questions-II (SAQs-II): 3 Marks


Q1. An element A reacts with water to form a compound B which is used in white washing. The compound B which is used white washing. The compound B on heating forms an oxide C which on treatment with water gives back B. Identify A,B and C and give reaction involved. 
Answer
Element A is Calcium (ca, when it reacts with water, it form Calcium hydroxide (Ca(OH)2, which is used in white washing.
Ca+2H2O→Ca(OH)2+H2 (g)
Compound B on heating gives CaO
Therefore,  C is Calcium Oxide (CaO).
Ca(OH)2→CaO+H2O
CaO+H2O→Ca(OH)2

Q2. Two Ores on Heating, A gives CO2, whereas ore B gives SO2. Explain the processes with help of balanced chemical equation, which is used to convert ores A and B into their oxide ores with an example.
Answer
Ore A is Carbonate Ore, 
The process involved in converting ores 
Calcination: The Carbonate ore is heated strongly in absence of air. 
ZnCO3→ZnO+CO2
Roasting: The sulphide ore is heated strongly in presence of excess of air, this is known as roasting.
ZnSO3→ZnO+SO2

Q3. Explain the formation of MgO by transfer of Electrons. 
Answer
Formation of MgO
Magnesium losses two electrons,  and forms Magnesium ions, to complete its octet. 
Mg→Mg2++2e-
Oxygen gains that two electrons to become O2-
Mg2++O2-→MgO
Q4.  Explain any 3 methods used for preventing Corrosion of metals?
Answer
Alloying: Mixing of the metal with another metal or non-metal can help in preventing Corrosion of metals. 
Example:- alloying Iron with Carbon to form steel
Electroplating: Platting a layer of Chromium over the surface of metal can help in preventing metals from getting corroded.
Galvanization: Iron metal is dipped in molten zinc, which forms a layer of zinc over Iron.

Long Answer Questions (LAQs): 5 Marks

Q1. (a) What concentration of Ore means?
(b) Explain Electrolytic Refining of metals which is obtained?

Answer

(a) Concentration or enrichment of ore means to remove impurities (gauge) particles from the ore particles.
(b) Electrolytic refining is the process of further refining or purification of obtained metal from the metallurgical processes. 
In this process
Initial Arrangement:
Anode is Impure block of Copper which is to be refined. 
Cathode is pure strip of Copper metal.
Electrolyte is solution of Copper Sulphate.
Working:
At Anode:
Copper from impure block of copper gains positive charge and generated Copper ions go to electrolytic solution of copper sulphate.

At Cathode:
Positively charged copper ions from electrolytic solution of  copper sulphate goes to Cathode. It is accumulated at Cathode.

Q2. (a) When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on adding potassium metal to water catches fire. Explain why ? 
(b) Name a metal for each case : 
(i) It displaces hydrogen gas from nitric acid. 
(ii) It does not react with any physical state of water. 
(iii) It does not react with cold as well as hot water but reacts with steam. 

Answer

(a) In both cases, the gas evolved is H2. When calcium reacts with water the heat evolved is not sufficient for hydrogen to catch fire. On the other hand, potassium reacts with water violently and lot of heat is evolved which is sufficient for hydrogen to catch fire. 
(b) (i) Zinc 
(ii) Copper 
(iii) Aluminium



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