Occurrence Questions in English

(A) An ore is a mineral from which a metal can be extracted economically and conveniently.
Since not all minerals contain a high enough concentration of metal to make extraction profitable,all ores are minerals,but not all minerals are ores.

(D) The chemical formulas for the given minerals are:
$1$. Cryolite: $Na_3AlF_6$ (contains $Al$)
$2$. Mica: $KAl_2(AlSi_3O_{10})(OH)_2$ (contains $Al$)
$3$. Feldspar: $KAlSi_3O_8$ (contains $Al$)
$4$. Fluorspar: $CaF_2$ (does not contain $Al$)
Therefore,Fluorspar is the mineral that does not contain $Al$.

(A) The chemical formula for Argentite is $Ag_2S$,which is a primary ore of silver.
Stibnite is an ore of antimony $(Sb_2S_3)$.
Hematite is an ore of iron $(Fe_2O_3)$.
Bauxite is an ore of aluminium $(AlO_x(OH)_{3-2x})$.
Therefore,the correct option is $A$.

(D) $1$. Dolomite is $CaCO_3 \cdot MgCO_3$,which is an ore of magnesium and calcium.
$2$. Galena is $PbS$,which is an ore of lead.
$3$. Magnesite is $MgCO_3$,which is an ore of magnesium.
$4$. Cassiterite is $SnO_2$,which is the primary ore of tin $(Sn)$.
Therefore,the correct statement is that Cassiterite is an ore of tin.

(B) mineral is a naturally occurring substance containing metal in combined form. An ore is a mineral from which a metal can be extracted conveniently and profitably. Therefore,the correct condition for a mineral to be called an ore is that the metal can be extracted from it profitably.

(B) Cinnabar is the common name for the mineral form of mercury$(II)$ sulfide,which has the chemical formula $HgS$. It is the principal ore of mercury.

(B) Sterling silver is an alloy of silver containing $92.5\%$ by mass of silver and $7.5\%$ by mass of copper.
In terms of parts per $1000$,$925$ sterling silver means it contains $925$ parts of silver and $75$ parts of copper.
Therefore,it is composed of $92.5\% Ag$ and $7.5\% Cu$.

(D) Corundum is a crystalline form of aluminum oxide $(Al_2O_3)$.
It is a naturally occurring mineral and is the primary source of aluminum in the form of anhydrous oxide.
Therefore,the correct chemical formula is $Al_2O_3$.

(C) Hematite is $Fe_2O_3$.
Magnetite is $Fe_3O_4$.
Limonite is $Fe_2O_3 \cdot 3H_2O$.
Cassiterite is $SnO_2$,which is an ore of tin $(Sn)$,not iron $(Fe)$.

(D) The Earth is divided into different zones based on the affinity of elements for different phases.
$1$. $Lithophil$ elements are found in the silicate layer (crust).
$2$. $Calcophil$ (or $Chalcophil$) elements are found in the sulphide layer.
$3$. $Siderophil$ elements are iron-loving elements that are primarily found in the Earth's core,which is composed mainly of iron and nickel.
Therefore,the region where main metals (like $Fe$,$Ni$) are concentrated is the $Siderophil$ zone.
The correct option is $(d)$.

(B) Gold $(Au)$,Silver $(Ag)$,and Platinum $(Pt)$ are known as noble metals.
These metals are highly unreactive due to their low chemical reactivity and are therefore found in their native or free state in nature.

(B) Copper metal is found in the Khetri region of Rajasthan.
Additionally,it is also found in the Singhbhum and Hazaribagh districts in Bihar,Agnigundala in Andhra Pradesh,and Malanjkhand in $M.P.$

(C) Sapphire is a gemstone variety of the mineral corundum,which is primarily composed of aluminum oxide $(Al_2O_3)$.
Therefore,it is a mineral of $Al$.

(C) The chemical formulas for the given substances are:
$1$. Bauxite: $Al_2O_3 \cdot 2H_2O$ (contains oxygen)
$2$. Epsom salt: $MgSO_4 \cdot 7H_2O$ (contains oxygen)
$3$. Cryolite: $Na_3AlF_6$ (does not contain oxygen)
$4$. Dolomite: $CaCO_3 \cdot MgCO_3$ (contains oxygen)
Therefore,the correct option is $(C)$.

(B) The chief impurity present in red bauxite is $Fe_2O_3$ (ferric oxide).
White bauxite contains $SiO_2$ as the main impurity,whereas red bauxite is rich in iron oxides.

(B) Thomas slag is chemically known as $Ca_3(PO_4)_2$ (calcium phosphate).
It is obtained as a byproduct during the manufacture of steel from phosphatic iron ore in the Bessemer process.
It is widely used as a valuable fertilizer in agriculture.

(B) The correct pair is $Copper : Malachite$.
$Malachite$ is a copper carbonate hydroxide mineral with the formula $Cu_2CO_3(OH)_2$.
$Calamine$ is an ore of $Zinc$ $(ZnCO_3)$.
$Carnallite$ is an ore of $Potassium$ and $Magnesium$ $(KMgCl_3 \cdot 6H_2O)$.
Therefore,option $B$ is correct.

(A) Most metal nitrates are highly soluble in water. Due to this high solubility,they are easily washed away by rain or groundwater and do not accumulate in the earth's crust to form stable mineral deposits or ores.
Statement $I$ is false because many metal nitrates are thermally stable (e.g.,alkali metal nitrates).
Statement $II$ is true because the high solubility prevents their accumulation in ores.
Therefore,the correct option is $A$.

(D) The chemical compositions of the given minerals are as follows:
$1$. Malachite: $CuCO_{3} \cdot Cu(OH)_{2}$ (Copper ore)
$2$. Cassiterite: $SnO_{2}$ (Tin ore)
$3$. Pyrolusite: $MnO_{2}$ (Manganese ore)
$4$. Magnetite: $Fe_{3}O_{4}$ (Iron ore)
Therefore,$Magnetite$ is a mineral of iron.

(C) Gold $(Au)$ atoms are found in the free state because:
Metals that are least reactive exist in the free state in nature.
Some of the elements that are found in the free state in nature are Gold $(Au)$,Platinum $(Pt)$,and Silver $(Ag)$.
Therefore,Gold $(Au)$ is a metal that is found in the free state in nature.

(D) The chemical formulas for the given ores are:
$1$. Cryolite: $Na_3AlF_6$ (a fluoride halide ore).
$2$. Fluorspar: $CaF_2$ (a fluoride halide ore).
$3$. Horn silver: $AgCl$ (a chloride halide ore).
$4$. Limonite: $Fe_2O_3 \cdot 3H_2O$ (an oxide ore).
Since Limonite is an oxide ore and not a halide ore,the correct option is $D$.

(D) The chemical formulas for the given minerals are:
$1$. Copper pyrite: $CuFeS_2$ (contains iron)
$2$. Iron pyrite: $FeS_2$ (contains iron)
$3$. Ilmenite: $FeTiO_3$ (contains iron)
$4$. Tincal: $Na_2B_4O_7 \cdot 10H_2O$ (does not contain iron)
Therefore,Tincal is the correct answer.

(B) The reaction $ACl_2 + BCl_2 \rightarrow ACl_4 + B \downarrow$ indicates that $A$ is oxidized from $+2$ to $+4$ and $B$ is reduced from $+2$ to $0$.
This behavior is characteristic of $Sn$ $(A)$ and $Hg$ $(B)$,where $SnCl_2$ acts as a reducing agent.
The thermal decomposition of $BO$ $(HgO)$ at temperatures $> 400 \ ^oC$ yields $Hg$ and $O_2$ $(HgO \rightarrow Hg + \frac{1}{2} O_2)$.
Since $B$ is $Hg$,its common ore is $HgS$,which is known as Cinnabar.

(D) The chemical formulas for the given ores are:
$(I)$ Cuprite: $Cu_2O$ (Oxide ore)
$(II)$ Argentite: $Ag_2S$ (Sulphide ore)
$(III)$ Pyrites: $FeS_2$ (Sulphide ore)
$(IV)$ Siderite: $FeCO_3$ (Carbonate ore)
From the above,Cuprite $(Cu_2O)$ and Siderite $(FeCO_3)$ do not contain sulphur.
Therefore,the correct option is $(I, IV)$.

(D) Cryolite: $Na_{3}AlF_{6}$ (sodium hexafluoroaluminate).
Mica: $KAl_{3}Si_{3}O_{10}(OH)_{2}$ (potassium aluminium silicate).
Feldspar: $KAlSi_{3}O_{8}$,$NaAlSi_{3}O_{8}$,or $CaAl_{2}Si_{2}O_{8}$ (aluminosilicates).
Fluorspar: $CaF_{2}$ (calcium fluoride).
Among the given options,only fluorspar does not contain $Al$. Hence,option $D$ is correct.

(C) An ore is a naturally occurring mineral from which a metal can be profitably extracted.
$A$. Malachite is an ore of copper $(Cu_2(OH)_2CO_3)$.
$B$. Calamine is an ore of zinc $(ZnCO_3)$.
$C$. Stellite is an alloy of $Co, Cr, W$ and $Fe$,not an ore.
$D$. Cerussite is an ore of lead $(PbCO_3)$.
Therefore,Stellite is not an ore.

(C) $1$. Magnetite is $Fe_3O_4$,which is an oxide ore of iron,not manganese.
$2$. Pyrolusite is $MnO_2$,which is an oxide ore of manganese,not lead.
$3$. Siderite is $FeCO_3$,which is a carbonate ore of iron. This is a correct statement.
$4$. $FeS_2$ is known as iron pyrites or fool's gold,not rolled gold. Rolled gold is an alloy of copper and aluminium.

(A) The three most abundant elements in the earth's crust by mass are Oxygen $(O)$,Silicon $(Si)$,and Aluminium $(Al)$.
Oxygen constitutes approximately $46.6\%$,Silicon $27.7\%$,and Aluminium $8.1\%$ of the earth's crust.
Hence,Option $A$ is the correct answer.

(A) Fool's gold is the common name for the mineral $FeS_2$,which is chemically known as iron pyrites. It is called 'Fool's gold' because its metallic luster and pale brass-yellow hue give it a superficial resemblance to gold.

(D) The correct matches for the given ores are:
$1$. $Carnallite$ is $KCl \cdot MgCl_2 \cdot 6H_2O$,which is an ore of $Potassium$ and $Magnesium$.
$2$. $Calamine$ is $ZnCO_3$,which is an ore of $Zinc$.
$3$. $Ilmenite$ is $FeTiO_3$,which is an ore of $Titanium$.
$4$. $Chalcopyrite$ is $CuFeS_2$,which is an ore of $Copper$.
Therefore,the only correctly matched pair is $Chalcopyrite \rightarrow Copper$.

(A) The correct match is $Zinc \rightarrow Calamine$.
$Calamine$ is $ZnCO_3$,which is a common ore of $Zinc$.
$Azurite$ is a copper ore $(Cu_3(CO_3)_2(OH)_2)$.
$Cassiterite$ is the primary ore of $Tin$ $(SnO_2)$.
$Ilmenite$ is an ore of $Titanium$ $(FeTiO_3)$.

(D) Peacock ore is the common name for the mineral bornite.
Its chemical formula is $Cu_5FeS_4$.

(B) The chemical formula of Chromite ore is $FeCr_2O_4$ (or $FeO \cdot Cr_2O_3$).
It is a mixed oxide of iron $(Fe^{2+})$ and chromium $(Cr^{3+})$.
Haematite is $Fe_2O_3$ (an oxide of iron).
Coleomanite is $Ca_2B_6O_{11} \cdot 5H_2O$ (a borate mineral).
Tincal is $Na_2B_4O_7 \cdot 10H_2O$ (a borate mineral).
Therefore,Chromite is the correct answer.

(B) The correct matches are as follows:
$1$. Chromite is $FeO \cdot Cr_2O_3$ $(Q)$.
$2$. Malachite is $CuCO_3 \cdot Cu(OH)_2$ $(R)$.
$3$. Cryolite is $Na_3AlF_6$ $(S)$.
$4$. Zinc Blende is $ZnS$ $(P)$.
Therefore,the correct sequence is $1-Q, 2-R, 3-S, 4-P$.

(B) Metal nitrates are generally not found in ores because they are highly soluble in water.
Due to their high solubility,they get washed away by rain or groundwater and do not accumulate in the earth's crust to form stable mineral deposits.
Statement $(a)$ is false because many metal nitrates are thermally stable at room temperature.
Statement $(b)$ is true because the high solubility prevents their accumulation as ores.

(A) The following are the sulphide ores of the metals:
For $Ag$,it is Argentite $(Ag_2S)$.
For $Pb$,it is Galena $(PbS)$.
For $Cu$,it is Copper glance $(Cu_2S)$.
Hence,option $A$ is correct.

(B) Azurite is a copper mineral with the chemical formula $2CuCO_3 \cdot Cu(OH)_2$.
It is a basic copper carbonate mineral.

(B) Metals that are least reactive are found in the native or free state in nature.
Among the given options,$Al$,$Fe$,and $Mg$ are highly reactive and are found in the form of oxides,carbonates,or silicates.
$Cu$ (Copper) is a noble metal with low reactivity and can be found in the native state,although it is also found as sulfide or oxide ores.

(A) Calamine is a mineral consisting of zinc carbonate. Its chemical formula is $ZnCO_3$.

(D) Malachite is a green-colored copper carbonate hydroxide mineral.
Its chemical formula is $Cu(OH)_2 \cdot CuCO_3$.

(A) Copper pyrites is $CuFeS_2$,which contains both iron and copper.
Malachite is $CuCO_3 \cdot Cu(OH)_2$,which contains only copper.
Azurite is $2CuCO_3 \cdot Cu(OH)_2$,which contains only copper.
Dolomite is $CaCO_3 \cdot MgCO_3$,which contains calcium and magnesium.

(B) The correct matches are as follows:
$I$. Siderite $(FeCO_3)$ $\to$ $c$. Iron $(Fe)$
$II$. Kaolinite $(Al_2Si_2O_5(OH)_4)$ $\to$ $d$. Aluminium $(Al)$
$III$. Malachite $(CuCO_3 \cdot Cu(OH)_2)$ $\to$ $b$. Copper $(Cu)$
$IV$. Calamine $(ZnCO_3)$ $\to$ $a$. Zinc $(Zn)$
Therefore,the correct sequence is $I-c, II-d, III-b, IV-a$.

(D) The chemical formula of cryolite is $Na_3[AlF_6]$.
It is a fluoride ore of aluminum.

(A) The chemical formulas for the given ores are:
$1$. Bauxite: $Al_2O_3 \cdot 2H_2O$ (an oxide ore).
$2$. Siderite: $FeCO_3$ (a carbonate ore).
$3$. Calamine: $ZnCO_3$ (a carbonate ore).
$4$. Malachite: $CuCO_3 \cdot Cu(OH)_2$ (a carbonate ore).
Therefore,bauxite is the only ore listed that is not a carbonate.

(C) The extraction of $Fe$ is primarily done from haematite ore $(Fe_2O_3)$,which is an oxide ore,not a carbonate ore.
Therefore,the assertion is correct,but the reason is incorrect.

(C) Black Jack is a common name for the mineral sphalerite,which is the primary ore of zinc. Its chemical formula is $ZnS$.

(D) The chemical formulas for the given minerals are:
$1$. Dolomite: $CaCO_3 \cdot MgCO_3$ (Contains $Ca$ and $Mg$)
$2$. Copper pyrite: $CuFeS_2$ (Contains $Cu$ and $Fe$)
$3$. Carnallite: $KCl \cdot MgCl_2 \cdot 6H_2O$ (Contains $K$ and $Mg$)
$4$. Chlorapatite: $Ca_9(PO_4)_6 \cdot CaCl_2$ (Contains only $Ca$ as a metal)
Therefore,Chlorapatite does not contain two different types of metals.

(B) The elements $Zn, Cu,$ and $Pb$ mostly occur as sulphide ores.
For example,$Zn$ occurs as zinc blende $(ZnS)$.
$Cu$ occurs as copper glance $(Cu_2S)$ and chalcopyrite $(CuFeS_2)$.
$Pb$ occurs as galena $(PbS)$.

(B) The correct matches are:
$A$. Tin corresponds to $2$. Cassiterite $(SnO_2)$.
$B$. Zinc corresponds to $1$. Calamine $(ZnCO_3)$.
$C$. Titanium corresponds to $4$. Rutile $(TiO_2)$.
$D$. Lead corresponds to $3$. Cerrusite $(PbCO_3)$.
Therefore,the correct sequence is $A-2, B-1, C-4, D-3$.