Which of the following property is generally not shown by metals?
Electrical conduction
Sonorous in nature
Dullness
Ductility
The ability of metals to be drawn into thin wire is known as
ductility
malleability
sonorousity
conductivity
Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
(i) and (ii)
(i) and (iii)
(ii) and (iii)
(i) and (iv)
Which one of the following metals do not react with cold as well as hot water?
Na
Ca
Mg
Fe
Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?
FeO
Fe2O3
Fe3O4
Fe2O3 and Fe3O4
What happens when calcium is treated with water?
(i) It does not react with water
(ii) It reacts violently with water
(iii) It reacts less violently with water
(iv) Bubbles of hydrogen gas formed stick to the surface of calcium
(i) and (iv)
(ii) and (iii)
(i) and (ii)
(iii) and (iv)
Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?
H2SO4
HCl
HNO3
All of these
The composition of aqua regia is
Dil. HCl 3 : Conc. HNO3 1
Conc. HCl 3 : Dil. HNO3 1
Conc. HCl 3 : Conc. HNO3 1
Dil. HCl 3 : Dil. HNO3 1
Which of the following are not ionic compounds?
(i) KCl
(ii) HCl
(iii) CCl4
(iv) NaCl
(i) and (ii)
(ii) and (iii)
(iii) and (iv)
(i) and (iii)
Which one of the following properties is not generally exhibited by ionic compounds?
Solubility in water
Electrical conductivity in solid state
High melting and boiling points
Electrical conductivity in molten state
Which of the following metals exist in their native state in nature?
(i) Cu
(ii) Au
(iii) Zn
(iv) Ag
(i) and (ii)
(ii) and (iii)
(ii) and (iv)
(iii) and (iv)
Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?
(i) Au
(ii) Cu
(iii) Na
(iv) K
(i) and (ii)
(i) and (iii)
(ii) and (iii)
(iii) and (iv)
Silver articles become black on prolonged exposure to air. This is due to formation of
Ag3N
Ag2O
Ag2S
Ag2S and Ag3N
Galvanisation is a method of protecting iron from rusting by coating with a thin layer of
Gallium
Aluminium
Zinc
Silver
Stainless steel is very useful material for our life. In stainless steel, iron is mixed with
Ni and Cr
Cu and Cr
Ni and Cu
Cu and Au
If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of
CuSO4
CuCO3
Cu(NO3)2
CuO
Generally, metals are solid in nature. Which one of the following metals is found in liquid state at room temperature?
Na
Fe
Cr
Hg
Which of the following metals are obtained by electrolysis of their chlorides in molten state?
(i) Na
(ii) Ca
(iii) Fe
(iv) Cu
(i) and (iv)
(iii) and (iv)
(i) and (ii)
(i) and (ii)
Which of the following statements are correct for magnesium?
(i) It burns in oxygen with a dazzling white flame
(ii) It reacts with cold water
(iii) It reacts with hot water
(iv) It reacts with steam
(i) and (ii)
(i) and (iii)
(i) and (iv)
(iii) and (iv)
Which among the following alloys contain mercury as one of its constituents?
Stainless steel
Alnico
Solder
Zamcudum amalgam
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
calcium
carbon
silicon
iron
Food cans are coated with tin and not with zinc because
zinc is costlier than tin
zinc has a higher melting point than tin
zinc is more reactive than tin
zinc is less reactive than tin
A metal that exists in the liquid state at room temperature is
Na
K
Hg
Ca
Which of the following metals is preserved in kerosene?
Na
Ca
Mg
Al
Which of the following gives the correct increasing order of reactivity?
Mg > Al > Zn > Fe
Fe > Zn > Al > Mg
Zn > Fe > Mg > Al
Al > Zn > Mg > Fe
Galvanised iron sheets are coated with a layer of
Al
Zn
Sn
Cu
Bronze is an alloy of
Cu and Sn
Cu and Zn
Cu and Ni
Cu and Al
The metal used for making filaments of bulbs is
Cu
Fe
Al
W
Which of the following metals is the most reactive?
Cu
Mg
Na
Zn
Which of the following metals will displace hydrogen from steam?
Zn
Mg
Sn
Fe
Which of the following metals cannot be obtained by reduction of their oxides with carbon?
Zn
Al
Fe
Pb
An iron nail is kept immersed in copper sulphate solution. The solution will turn
blue
green
yellow
colorless
Which of the following metals will not replace hydrogen from acids?
Zn
Al
Cu
Mg
Which of the following set of reactions will occur?
(i) Zn + CuSO4 → ?
(ii) Fe + CuSO4 → ?
(iii) Cu + FeSO4 → ?
(iv) Zn + FeSO4 → ?
(i), (ii), (iii)
(i), (ii), (iv)
(ii), (iii), (iv)
(i), (iii), (iv)
Which of the following metals occurs in native state?
Na
Zn
Au
Al
Which of the following metals produces hydrogen gas on reaction with nitric acid?
Zn
Cu
Ag
Au
Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both the reactions.
The gas can be identified by bringing a burning matchstick near the reaction vessel; a pop sound is produced.
\( M + 2NaOH \rightarrow Na_2M O_2 + H_2 \)
\( M + 2HCl \rightarrow MCl_2 + H_2 \)
The element is a metal.
During extraction of metals, electrolytic refining is used to obtain pure metals. (a) Which material will be used as anode and cathode for refining of silver metal by this process? (b) Suggest a suitable electrolyte also. (c) In this electrolytic cell, where do we get pure silver after passing electric current?
(a) Anode: Impure silver
Cathode: Pure silver
(b) Electrolyte: Silver salt such as \( AgNO_3 \)
(c) Pure silver is obtained at the cathode.
Why should the metal sulphides and carbonates be converted to metal oxides in the process of extraction of metal from them?
It is easier to obtain metal from its oxide as compared with its sulphides and carbonates.
Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg) treated with \( HNO_3 \), hydrogen is not liberated. Why?
Because \( HNO_3 \) is a strong oxidising agent. It oxidises the \( H_2 \) produced to \( H_2O \).
Compound X and aluminium are used to join railway tracks. (a) Identify compound X. (b) Name the reaction. (c) Write down its reaction.
(a) X is \( Fe_2O_3 \)
(b) Thermite reaction
(c) \( Fe_2O_3(s) + 2Al(s) \rightarrow 2Fe(l) + Al_2O_3(s) + \text{Heat} \)
When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.
\( X = Na \)
\( Y = NaOH \)
\( Z = H_2 \)
Reaction: \( 2Na + 2H_2O \rightarrow 2NaOH + H_2 + \text{Heat} \)
A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.
X — Carbon
Y — Diamond
Z — Graphite
The following reaction takes place when aluminium powder is heated with \( MnO_2 \):
\( 3MnO_2(s) + 4Al(s) \rightarrow 3Mn(l) + 2Al_2O_3(l) + \text{Heat} \)
(a) Is aluminium getting reduced? (b) Is \( MnO_2 \) getting oxidised?
(a) No. Oxygen is added to aluminium; therefore, it is getting oxidised.
(b) No. Since manganese has lost oxygen, it is getting reduced.
What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?
Solder is an alloy of lead and tin. Its low melting point makes it suitable for welding electrical wires.
A metal A, which is used in thermite process, when heated with oxygen gives an oxide B which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCl and NaOH.
A = Al
B = \( Al_2O_3 \)
\( Al_2O_3 + 6HCl \rightarrow 2AlCl_3 + 3H_2O \)
\( Al_2O_3 + 2NaOH \rightarrow 2NaAlO_2 + H_2O \)
A metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved.
Metal: Mercury (Hg)
Ore: Cinnabar (HgS)
Reactions:
\( 2HgS + 3O_2 \xrightarrow{\text{Heat}} 2HgO + 2SO_2 \)
\( 2HgO \xrightarrow{\text{Heat}} 2Hg + O_2 \)
Give the formulae of the stable binary compounds that would be formed by the combination of following pairs of elements.
(a) Mg and N2
(b) Li and O2
(c) Al and Cl2
(d) K and O2
(a) \( Mg_3N_2 \)
(b) \( Li_2O \)
(c) \( AlCl_3 \)
(d) \( K_2O \)
What happens when
(a) \( ZnCO_3 \) is heated in the absence of oxygen?
(b) A mixture of \( Cu_2O \) and \( Cu_2S \) is heated?
(a) It undergoes calcination:
\( ZnCO_3 \xrightarrow{\text{Heat}} ZnO + CO_2 \)
(b) It undergoes auto-reduction forming copper and sulphur dioxide:
\( 2Cu_2O + Cu_2S \xrightarrow{\text{Heat}} 6Cu + SO_2 \)
A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas C causes global warming.
(a) Identify A, B and C.
(b) To which group of Periodic Table does A belong?
(a) A = Carbon, B = Carbon monoxide, C = Carbon dioxide
(b) A belongs to Group 14 of the Periodic Table.
Give two examples each of the metals that are good conductors and poor conductors of heat respectively.
Good conductors: Ag, Cu
Poor conductors: Pb, Hg
Name one metal and one non-metal that exist in liquid state at room temperature. Also name two metals having melting point less than 310 K (37°C).
Metal (liquid): Mercury (Hg)
Non-metal (liquid): Bromine (Br)
Metals with melting point less than 310 K: Caesium (Cs), Gallium (Ga)
An element A reacts with water to form a compound B which is used in 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 the reactions involved.
A = Ca
B = Ca(OH)2
C = CaO
\( Ca(s) + 2H_2O \rightarrow Ca(OH)_2(aq) + H_2(g) \)
\( Ca(OH)_2 \xrightarrow{\text{Heat}} CaO + H_2O \)
\( CaO + H_2O \rightarrow Ca(OH)_2 \)
An alkali metal A gives a compound B (molecular mass = 40) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.
A = Na
B = NaOH
C = NaAlO2
\( 2Na + 2H_2O \rightarrow 2NaOH + H_2 \)
\( Al_2O_3 + 2NaOH \rightarrow 2NaAlO_2 + H_2O \)
Give the reaction involved during extraction of zinc from its ore by
(a) roasting of zinc ore
(b) calcination of zinc ore
(a) Roasting:
\( 2ZnS + 3O_2 \xrightarrow{\text{Heat}} 2ZnO + 2SO_2 \)
(b) Calcination:
\( ZnCO_3 \xrightarrow{\text{Heat}} ZnO + CO_2 \)
A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black coloured product. Identify M and the black coloured product and also explain the reaction of M with oxygen.
M = Cu
Black product = CuO
Reaction: \( 2Cu + O_2 \rightarrow 2CuO \)
An element forms an oxide \( A_2O_3 \) which is acidic in nature. Identify A as a metal or non-metal.
Since the oxide is acidic in nature, A is a non-metal.
A solution of \( CuSO_4 \) was kept in an iron pot. After few days the iron pot was found to have a number of holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.
Iron is more reactive than copper. It displaces copper from copper sulphate solution and forms iron sulphate. The displaced copper deposits on the pot and iron dissolves gradually, forming holes.
\( Fe + CuSO_4 \rightarrow FeSO_4 + Cu \)
A non-metal A, which is the largest constituent of air, reacts with hydrogen in a 1:3 ratio in the presence of a catalyst to form a gas B. On heating B with oxygen, it produces an oxide C. When this oxide is passed into water in the presence of air, it produces an acid D that acts as a strong oxidising agent. Identify A, B, C and D, and state the group of the periodic table to which A belongs.
Identification:
A — Nitrogen (\(N_2\))
B — Ammonia (\(NH_3\))
C — Nitric oxide (\(NO\))
D — Nitric acid (\(HNO_3\))
Stepwise reactions:
Formation of ammonia:
\[ N_2 + 3H_2 \rightarrow 2NH_3 \]
Formation of nitric oxide:
\[ 4NH_3 + 5O_2 \xrightarrow{heat} 4NO + 6H_2O \]
Formation of nitric acid:
\[ 2NO + O_2 \rightarrow 2NO_2 \]
\[ 4NO_2 + 2H_2O + O_2 \rightarrow 4HNO_3 \]
Group of A: Nitrogen belongs to Group 15.
Describe the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.
Extraction from sulphide ore of low reactivity metals:
Roasting:
The sulphide ore is heated in the presence of air to convert it into oxide.
\[ 2MS + 3O_2 \rightarrow 2MO + 2SO_2 \]
Reduction:
The metal oxide is reduced to metal.
\[ MO + C \rightarrow M + CO \]
Refining:
The crude metal obtained is purified.
Extraction from sulphide ore of medium reactivity metals:
Roasting:
Ore is heated in excess air to remove sulphur.
Reduction:
The oxide formed after roasting is reduced to metal.
Refining:
The metal obtained is purified by electrolytic or other methods.
Explain each of the following:
Reactivity of aluminium decreases if it is dipped in \(HNO_3\).
Carbon cannot reduce the oxides of sodium or magnesium.
Sodium chloride does not conduct electricity in the solid state, but conducts in aqueous or molten state.
Iron articles are galvanised.
Metals like Na, K, Ca and Mg are never found in free state.
Aluminium in \(HNO_3\):
Aluminium reacts with nitric acid to form a protective oxide layer of \(Al_2O_3\), preventing further reaction. This decreases its reactivity.
Carbon cannot reduce Na or Mg oxides:
Metals like Na and Mg are more reactive than carbon. Their oxides are very stable, so carbon cannot reduce them.
Conductivity of NaCl:
In solid NaCl, ions are fixed in a rigid lattice and cannot move, so electricity is not conducted. In molten or aqueous NaCl, ions can move freely, enabling conduction.
Galvanisation:
Iron is galvanised by coating with zinc to prevent corrosion and rusting.
Highly reactive metals:
Na, K, Ca and Mg react quickly with air, water or other elements and therefore occur only as compounds in nature.
Given below are the steps involved in the extraction of copper from its ore. Write the reactions involved and draw a labelled diagram for electrolytic refining of copper.
(a) Roasting of copper(I) sulphide
(b) Reduction of copper(I) oxide with copper(I) sulphide
(c) Electrolytic refining
(a) Roasting of copper(I) sulphide:
\[ 2Cu_2S(s) + 3O_2(g) \xrightarrow{heat} 2Cu_2O(s) + 2SO_2(g) \]
(b) Reduction of copper(I) oxide with copper(I) sulphide:
\[ 2Cu_2O + Cu_2S \xrightarrow{heat} 6Cu + SO_2 \]
This is known as auto-reduction.
(c) Electrolytic refining:
At cathode:
\[ Cu^{2+}(aq) + 2e^- \rightarrow Cu(s) \]
At anode:
\[ Cu(s) \rightarrow Cu^{2+}(aq) + 2e^- \]
Diagram:
(A labelled diagram showing anode, cathode, electrolyte (acidified copper sulphate), and impurities such as anode mud.)
Three metals X, Y and Z react differently with water. X reacts with cold water, Y with hot water, and Z with steam only. Identify X, Y and Z and arrange them in order of increasing reactivity.
Identification:
X — Sodium, Potassium (alkali metals)
Y — Magnesium or Calcium (alkaline earth metals)
Z — Iron
Order of increasing reactivity:
\[ Fe < Mg < Na \]
Alkali metals react most vigorously with water, alkaline earth metals react moderately, and iron reacts only with steam.
An element A burns with a golden flame in air. It reacts with another element B (atomic number 17) to give product C. An aqueous solution of C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D, and write all reactions involved.
Identification:
A — Sodium (Na)
B — Chlorine (\(Cl_2\))
C — Sodium chloride (\(NaCl\))
D — Sodium hydroxide (\(NaOH\))
Reactions involved:
Formation of sodium chloride:
\[ 2Na + Cl_2 \rightarrow 2NaCl \]
Electrolysis of aqueous sodium chloride:
\[ 2NaCl(aq) + 2H_2O(l) \rightarrow 2NaOH(aq) + Cl_2(g) + H_2(g) \]
Two ores A and B were taken. On heating, ore A gives \(CO_2\), whereas ore B gives \(SO_2\). What steps will you take to convert both ores into metals?
Since ore A gives \(CO_2\), it is a carbonate ore (\(MCO_3\)).
Step 1: Calcination:
\[ MCO_3 \xrightarrow{heat} MO + CO_2 \]
Step 2: Reduction:
\[ MO + C \rightarrow M + CO \]
Since ore B gives \(SO_2\), it is a sulphide ore (\(MS\)).
Step 1: Roasting:
\[ 2MS + 3O_2 \rightarrow 2MO + 2SO_2 \]
Step 2: Reduction:
\[ MO + C \rightarrow M + CO \]