Thursday, August 9, 2012

10th Metal and non metal (2 marks questions ) By Jsunils

2 marks questions (short answer type question)
Q.1:- Name two metals that react with dil.HNO3 to evolve H2 gas ?
Ans:- magnesium and manganese 
Q.2:- What would you observe when zinc is added to a solution of iron(II) sulphate ?write the chemical reaction that takes place.
Ans:- The solution of iron(II) sulphate slowly turns to colourless and grey coloured layer of Fe is deposited on the surface of zinc metal.
Zn(s) + FeSO4(aq) ------->ZnSO4(aq) + Fe(s)
Q. 3:- Why ionic compounds have high melting points?
Ans:- Ionic solids have crystalline structure in which there is strong interionic attraction. So large amount of energy is needed to overcome this force of attraction.
Q. 4:- What do you mean by roasting? How it is different from calcination? In which types of ores roasting is done?
Ans:- Heating an ore strongly in excess of air is called roasting. This is done to convert sulphide ores into its oxide form. Calcination is different from roasting because it is done in absence of air.   2ZnS(s) + 3O2(g) heat -----à 2ZnO(s) + 2SO2
Q.5:- Define :- (i) Ore, (ii) Mineral.
Ore:- The minerals from which an element can be extracted profitably and conveniently is called ore. E.g. - Bauxite, Al2O3.2H2O – is an ore of aluminum.
Mineral:- The compounds of elements that occurs naturally in earth‘s crust are called minerals. E.g.- Glauber‘s salt Na2SO4.7H2O; Borax Na2B4O7.10H20 are two mineral sources of Sodium.
Q.6:- Name two metals which are found in nature in the Free State.
Ans:- Silver and Gold.
Q.7:- Define :- (i) Enrichment of Ores (ii) Gangue.
(i) Removal of earthly impurities like sand, clay from an ore is called enrichment of ore.
(ii) The earthy impurities like sand, clay that are found along with an ore are called gangue or matrix.
Q.8:- Write short notes on electrolytic refining of metals.
Ans:- In electrolytic refining the impure metal is taken as anode and the pure metal is taken as cathode. These two rods are dipped in aqueous salt solution of the same metal and electricity is passed. Pure metal from anode is dissolved into the solution and equivalent amount of pure metal from the electrolyte is deposited at the cathode
Q.9:- Name the conditions which are essential for corrosion.
Ans:- (i) Presence of moisture, (ii) Presence of air.
Q.10:- What is Galvanisation? Write its use.
Ans:- Galvanisation is a method of protecting steel and iron from rusting by coating them with a thin layer of Zinc.

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