Occurrence Questions in English

(D) The correct matches are as follows:
$A$. Calamine $(ZnCO_3)$ is a Carbonate ore $(III)$.
$B$. Bauxite $(Al_2O_3 \cdot 2H_2O)$ is an Oxide ore $(IV)$.
$C$. Kaolinite $(Al_2(OH)_4Si_2O_5)$ is a Silicate mineral $(V)$.
$D$. Cryolite $(Na_3AlF_6)$ is a Halide ore $(II)$.
Therefore,the correct matching is $A-III, B-IV, C-V, D-II$.

(C) The percentage abundance of elements in the earth's crust by mass is as follows:
$1$. Oxygen $(O)$: $46.0\%$
$2$. Silicon $(Si)$: $27.7\%$
$3$. Aluminium $(Al)$: $8.3\%$
Given that $X = 27.7\%$,$Y = 8.3\%$,and $Z = 46.0\%$,we have:
$X = Si$
$Y = Al$
$Z = O$
Therefore,$X, Y$ and $Z$ are $Si, Al$ and $O$ respectively.

(A) Siderite is an important iron ore.
Its chemical composition is $FeCO_3$ (iron$(II)$ carbonate).
Therefore,the correct option is $A$.

(C) Kaolinite is a clay mineral with the chemical formula $Al_2Si_2O_5(OH)_4$,which contains the metal $Al$ (Aluminum).
Calamine is a zinc ore with the chemical formula $ZnCO_3$,which contains the metal $Zn$ (Zinc).
Therefore,$X$ is $Al$ and $Y$ is $Zn$.

(A) Sphalerite is the sulphide ore of zinc $(Zn)$,which has an atomic number of $30$.
Siderite is the carbonate ore of iron $(Fe)$,which has an atomic number of $26$.
Malachite is the carbonate hydroxide ore of copper $(Cu)$,which has an atomic number of $29$.
Therefore,the atomic numbers of $X$,$Y$,and $Z$ are $30, 26, 29$ respectively.

(C) Calamine $(ZnCO_3)$ is an ore of zinc $(Zn)$,while the others are ores of iron.
Hematite is $(Fe_2O_3)$.
Magnetite is $(Fe_3O_4)$.
Siderite is $(FeCO_3)$.

(A) The chemical compositions of the given ores are as follows:
$A$. Calamine: $ZnCO_3$ (matches with $ii$)
$B$. Chalcopyrite: $CuFeS_2$ (matches with $i$)
$C$. Bauxite: $Al_2O_3 \cdot 2H_2O$ (matches with $iv$)
$D$. Haematite: $Fe_2O_3$ (matches with $iii$)
Therefore,the correct matching is $A-ii, B-i, C-iv, D-iii$.

(C) Out of the given four elements $C$,$S$,$Fe$,and $Au$,the non-metals $C$ and $S$ exist in their elemental form as allotropes.
$Au$ is a noble metal with low reactivity,so it exists in nature in its elemental form,often called a nugget.
$Fe$ is an electropositive metal. Therefore,it is highly reactive and exists in the earth's crust only in a combined state (as compounds),such as $Fe_2O_3$,$Fe_3O_4$,and $FeS_2$.

(B) The correct set of sulphide ores is Sphalerite,Fool's gold,and Chalcopyrites.
$1$. Sphalerite is a zinc sulphide mineral with the chemical formula $ZnS$.
$2$. Fool's gold (Pyrite) is an iron sulphide with the chemical formula $FeS_2$.
$3$. Chalcopyrite is a copper iron sulphide mineral with the chemical formula $CuFeS_2$.

(C) The minerals and their formulas are as follows:

Mineral	Formula
Galena	$PbS$
Cerussite	$PbCO_3$
Cassiterite	$SnO_2$
Anglesite	$PbSO_4$

From the table,it is clear that $SnO_2$ (Cassiterite) is the mineral for tin $(Sn)$.
Therefore,the correct option is $C$.

(A) The correct matches are:
$(A)$ Feldspar: $KAlSi_3O_8$ $(IV)$
$(B)$ Asbestos: $CaMg_3(SiO_3)_4$ $(V)$
$(C)$ Pyrargyrite: $Ag_3SbS_3$ $(I)$
$(D)$ Diaspore: $Al_2O_3 \cdot H_2O$ $(II)$
Therefore,the correct sequence is $A-IV, B-V, C-I, D-II$.

(D) Cement is primarily composed of calcium oxide $(CaO)$ and silicon dioxide $(SiO_2)$.
Other significant components include aluminum oxide $(Al_2O_3)$,magnesium oxide $(MgO)$,iron oxide $(Fe_2O_3)$,and sulfur trioxide $(SO_3)$.
Among the given options,$SiO_2$ and $CaO$ constitute the largest percentage by mass in Portland cement.

(A) The chemical formula for the ore chromite is $FeCr_{2}O_{4}$.
It is an oxide mineral belonging to the spinel group.

(A) The abundance of metals in the earth's crust is as follows: $Aluminium$ $(Al)$ is the most abundant metal,accounting for approximately $8.3\%$ by weight. $Iron$ $(Fe)$ is the second most abundant metal. Therefore,the correct option is $A$.