Mix Examples of s-Block Elements Questions in English

(A) $NaOH$ is used in the purification of Bauxite $(a-s)$.
$Na_2CO_3$ is used in the manufacture of detergent soap $(b-r)$.
Liquid $Na$ is used as a coolant in nuclear reactors $(c-q)$.
Potassium is found in the mineral Silvine $(KCl)$ $(d-p)$.
Thus,the correct match is $(a-s), (b-r), (c-q), (d-p)$.

(A) $Ra$ (Radium) is a radioactive element $(a-s)$.
$K$ (Potassium) is used in photoelectric cells due to its low ionization energy $(b-r)$.
$Li$ (Lithium) is used in alloys for the aeroplane industry $(c-p)$.
$Na$ (Sodium) is extracted by the electrolysis of molten $NaCl$ in the Down cell $(d-q)$.
Therefore,the correct match is $a-s, b-r, c-p, d-q$.

(C) The composition of Portland cement is approximately:
$CaO$: $50-60\%$
$SiO_2$: $20-25\%$
$Al_2O_3$: $5-10\%$
$MgO$: $2-3\%$
$Fe_2O_3$: $1-2\%$
$SO_3$: $1-3\%$
Therefore,the correct matching is $1-d, 2-a, 3-b$.

(A) $1$. Sodium is used in color industries $(1-d)$.
$2$. Beryllium-copper alloys are used for preparing springs $(2-a)$.
$3$. Radium is used in the treatment of cancer $(3-b)$.
$4$. Magnesium-aluminium alloys are used in the preparation of aeroplanes $(4-c)$.
Therefore,the correct match is $1-d, 2-a, 3-b, 4-c$.

(A) The average composition of Portland cement is as follows:
$1$. $CaO$: $50-60\%$
$2$. $SiO_2$: $20-25\%$
$3$. $Al_2O_3$: $5-10\%$
$4$. $MgO$: $2-3\%$
Therefore,the correct matching is $1-b, 2-a, 3-d, 4-c$.

(C) The correct matches are as follows:
$1. CaCO_3$ is used as an antacid $(b)$.
$2. Ca(OH)_2$ is used in glass and leather industries $(d)$.
$3. CaO$ is used in the purification of coal gas $(a)$.
$4. Na_2CO_3 \cdot 10H_2O$ is used in paper and textile industries $(c)$.
Therefore,the correct sequence is $1-b, 2-d, 3-a, 4-c$.

(A-3, B-2, C-4, D-5) $A-3, B-2, C-4, D-5$
$(A)$ $Li$: Due to very high hydration enthalpy,$E^{\circ}$ is most negative.
$(B)$ $Na$: $Na$ gives $NaOH$ (strong base). One mole of it replaces $1 \ mol \ H^{+}$ from acid,therefore it is the strongest monoacidic base.
$(C)$ $Ca$: Hydration energy is low,therefore calcium oxalate is insoluble.
$(D)$ $Ba$: Hydration energy is low as the size of $Ba^{2+}$ is large,therefore barium sulphate is insoluble. $6s^2$ is the valence shell electronic configuration.

(N/A) Alkali metals form predominantly ionic compounds. Alkaline earth metals also form ionic compounds,but they exhibit a greater tendency to form covalent compounds compared to alkali metals due to their higher charge density and smaller ionic radii.
$(b)$ Alkali metal oxides are strongly basic and dissolve in water to form strong hydroxides. Alkaline earth metal oxides are also basic,but less so than alkali metal oxides; their solubility in water increases down the group.
$(c)$ Both groups form oxosalts (like carbonates,sulfates,and nitrates) with oxoacids. Alkali metals form these more readily due to their higher reactivity.
$(d)$ The solubility of oxosalts of alkali metals is generally higher than that of alkaline earth metals,although this depends on the specific anion and the balance between lattice enthalpy and hydration enthalpy.
$(e)$ Alkali metal oxosalts are generally more thermally stable than those of alkaline earth metals. For example,$Na_2CO_3$ is stable to heat,whereas $MgCO_3$ decomposes upon heating to form $MgO$ and $CO_2$.

(C) The $s$-block elements consist of two groups:
$1$. Alkali metals: $Li, Na, K, Rb, Cs, Fr$ (Group $1$).
$2$. Alkaline earth metals: $Be, Mg, Ca, Sr, Ba, Ra$ (Group $2$).

(D) $I. Ca(OH)_2$ is used for white washing.
$II. NaCl$ is used in the Solvay process for the preparation of washing soda $(Na_2CO_3)$:
$2NH_3 + H_2O + CO_2 \longrightarrow (NH_4)_2CO_3$
$(NH_4)_2CO_3 + H_2O + CO_2 \longrightarrow 2NH_4HCO_3$
$NH_4HCO_3 + NaCl \longrightarrow NH_4Cl + NaHCO_{3(s)}$
$2NaHCO_3 \xrightarrow{\Delta} Na_2CO_3 + CO_2 + H_2O$
$III. CaSO_4 \cdot \frac{1}{2}H_2O$ (Plaster of Paris) is used for making casts of statues.
$IV. CaCO_3$ is used as an antacid.

(D) $Ba$ $(Z=56)$ has the outer electronic configuration $6s^2$.
$(b)$ $Ca$ forms $CaC_2O_4$ (calcium oxalate),which is insoluble in water.
$(c)$ $Li$ compounds (like $LiCl$) are covalent in nature and are soluble in organic solvents due to high polarization.
$(d)$ $Na$ forms $NaOH$,which is a very strong monoacidic base.
Therefore,the correct matching is: $(a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)$.

(A) Chlorophyll contains $Mg^{2+}$ as the central metal ion.
Soda ash is the common name for anhydrous sodium carbonate,$Na_2CO_3$.
$CaSO_4$ (specifically Plaster of Paris,a hemihydrate of calcium sulfate) is used in dentistry and ornamental work.
$Ca(OH)_2$ (slaked lime) is used in white washing.
Therefore,the correct matching is $A-III, B-I, C-II, D-IV$.

(A) The flame test colors for the given elements are as follows:
$1$. Potassium $(K)$ imparts a $Violet$ color to the flame.
$2$. Calcium $(Ca)$ imparts a $Brick \ Red$ color to the flame.
$3$. Strontium $(Sr)$ imparts a $Crimson \ Red$ color to the flame.
$4$. Barium $(Ba)$ imparts an $Apple \ Green$ color to the flame.
Therefore,the correct matching is:
$A-I, B-II, C-III, D-IV$.

(B) The quality of Portland cement is determined by the ratio of lime $(CaO)$ to the total of the acidic oxides ($SiO_2$,$Al_2O_3$,and $Fe_2O_3$).
This ratio is given by the formula: $\frac{\% CaO}{\% SiO_2 + \% Al_2O_3 + \% Fe_2O_3} \approx 2.0$.
For a good quality cement,this ratio should be between $1.9$ and $2.1$,which is closest to $2$.
Therefore,option $(B)$ is correct.

(D) . $Na$ in excess $NH_3$ forms solvated electrons,which are paramagnetic.
$B$. $K + O_2$ (excess) $\rightarrow KO_2$. The superoxide ion $O_2^-$ has one unpaired electron,making it paramagnetic.
$C$. $Cu +$ dilute $HNO_3 \rightarrow Cu(NO_3)_2 + NO + H_2O$. $NO$ (nitric oxide) has an odd number of electrons $(15)$,making it paramagnetic.
$D$. $O_2 + 2-ethylanthraquinol \rightarrow 2-ethylanthraquinone + H_2O_2$. $H_2O_2$ is diamagnetic.
Therefore,the reagents yielding paramagnetic species are $A, B,$ and $C$.

(A) The general valence shell electronic configurations are as follows:
$A$. Alkali metals (Group $1$) have the configuration $ns^1$.
$B$. Alkaline earth metals (Group $2$) have the configuration $ns^2$.
$C$. Halogens (Group $17$) have the configuration $ns^2 np^5$.
$D$. Noble gases (Group $18$) have the configuration $ns^2 np^6$.
Therefore,the correct matching is $A-II, B-IV, C-III, D-I$.

(D) $I$) The stability of superoxide increases as the size of the alkali metal cation increases due to the stabilization of the large anion by the large cation. Thus,the order $NaO_2 < KO_2 < RbO_2 < CsO_2$ is correct.
$II$) The basic strength of alkaline earth metal hydroxides increases down the group as the solubility and ionic character increase. Thus,the order $Mg(OH)_2 < Ca(OH)_2 < Sr(OH)_2$ is correct.
$III$) The thermal stability of alkaline earth metal carbonates increases down the group as the electropositive character of the metal increases. Thus,the order $MgCO_3 < CaCO_3 < SrCO_3$ is correct.
Therefore,all three statements are correct.

(A) Portland cement is primarily composed of calcium silicates and aluminates.
The main constituents are tricalcium silicate $(3CaO \cdot SiO_2)$,dicalcium silicate $(2CaO \cdot SiO_2)$,tricalcium aluminate $(3CaO \cdot Al_2O_3)$,and tetracalcium aluminoferrite $(4CaO \cdot Al_2O_3 \cdot Fe_2O_3)$.
Among these,$CaO$ and $SiO_2$ are the most abundant components,with $CaO$ typically accounting for approximately $64 \%$ and $SiO_2$ for approximately $21 \%$ of the composition.

(C) When $Na_2O$ and $CaO$ are dissolved in water,they form $NaOH$ and $Ca(OH)_2$ respectively.
$Na_2O + H_2O \longrightarrow 2NaOH$
$CaO + H_2O \longrightarrow Ca(OH)_2$
When this mixture is saturated with excess $CO_2$,the hydroxides react to form bicarbonates:
$2NaOH + 2CO_2 \longrightarrow 2NaHCO_3$
$Ca(OH)_2 + 2CO_2 \longrightarrow Ca(HCO_3)_2$
Since $NaHCO_3$ is a salt of a strong base $(NaOH)$ and a weak acid $(H_2CO_3)$,the solution is basic due to the hydrolysis of the bicarbonate ion $(HCO_3^- + H_2O \rightleftharpoons H_2CO_3 + OH^-)$.

(C) $1$. Compound '$A$' is $Ca(OH)_2$ (slaked lime),which is used for water softening.
$2$. $Ca(OH)_2$ reacts with $Na_2CO_3$ to form $NaOH$ (compound '$B$') and $CaCO_3$ (precipitate). $NaOH$ is a strong base with $pH=14$.
$Ca(OH)_2 + Na_2CO_3 \rightarrow CaCO_3 + 2NaOH$
$3$. $Ca(OH)_2$ reacts with $CO_2$ to form $CaCO_3$,which appears as a cloudy precipitate.
$Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$
$4$. The mixture of $NaOH$ and $CaO$ is known as soda lime. It performs decarboxylation on organic acids. When $C_6H_5COOH$ (benzoic acid,compound '$C$') reacts with soda lime,it produces benzene $(C_6H_6)$.
$C_6H_5COOH + NaOH + CaO \xrightarrow{\Delta} C_6H_6 + Na_2CO_3$
Therefore,'$A$' is $Ca(OH)_2$,'$B$' is $NaOH$,and '$C$' is $C_6H_5COOH$.

(B) . $KOH$ is used as an absorbent for $CO_2$ $(A-IV)$.
$B$. Liquid sodium $(Na_{(l)})$ is used as a coolant in fast breeder nuclear reactors $(B-I)$.
$C$. $Li$ is used in electrochemical cells (e.g.,lithium-ion batteries) $(C-III)$.
$D$. $Mg(OH)_2$ is used as an antacid $(D-II)$.
Therefore,the correct matching is $A-IV, B-I, C-III, D-II$.

(C) The melting points of $s$-block elements depend on the strength of metallic bonding and crystal structure.
$Be$ (Beryllium) has a high melting point $(1560 \ K)$ due to its small size and strong metallic bonding.
$Mg$ (Magnesium) has a melting point of $923 \ K$.
$Li$ (Lithium) has a melting point of $453 \ K$.
$Na$ (Sodium) has a melting point of $371 \ K$.
Comparing these values: $1560 \ K (Be) > 923 \ K (Mg) > 453 \ K (Li) > 371 \ K (Na)$.
Thus,the correct order is $Be > Mg > Li > Na$.

(C) $1$. Thermal stability of alkaline earth metal carbonates increases down the group as the electropositive character increases: $BeCO_3 < MgCO_3 < CaCO_3 < SrCO_3$. Thus,option $A$ is correct.
$2$. Solubility of alkaline earth metal sulfates decreases down the group due to the decrease in hydration energy: $BeSO_4 > MgSO_4 > CaSO_4 > SrSO_4$. Thus,option $B$ is correct.
$3$. Thermal stability of alkali metal carbonates increases down the group: $Li_2CO_3 < Na_2CO_3 < K_2CO_3 < Rb_2CO_3$. The given order in option $C$ $(Li_2CO_3 > Na_2CO_3 > K_2CO_3 > Rb_2CO_3)$ is incorrect.
$4$. Solubility of carbonates of alkaline earth metals decreases down the group: $BeCO_3 > MgCO_3 > CaCO_3 > SrCO_3$. Thus,option $D$ is correct.

(B) $I$. $LiF$ is less soluble in water than $NaF$ due to its very high lattice energy. This statement is correct.
$II$. $LiCl$ and $MgCl_2$ are covalent in nature and are soluble in ethanol,not insoluble. This statement is incorrect.
$III$. Both $Li$ and $Mg$ show diagonal relationship and both form nitrides ($Li_3N$ and $Mg_3N_2$) on reaction with $N_2$. This statement is correct.
$IV$. $Na_2CO_3$ is thermally stable and does not decompose to give $CO_2$ on heating. This statement is incorrect.
Therefore,statements $I$ and $III$ are correct.

(A) The correct matches are as follows:
$(A)$ $Na_2O_2$ is used as an oxidising agent $(III)$.
$(B)$ $D_2O$ (heavy water) is used as a moderator in nuclear reactors $(IV)$.
$(C)$ $Cs$ (Cesium) is used in photoelectric cells due to its low ionisation energy $(I)$.
$(D)$ $Mg(OH)_2$ (milk of magnesia) is used as an antacid $(II)$.
Therefore,the correct matching is $A-III, B-IV, C-I, D-II$.

(D) $BeH_2$ and $MgH_2$ are electron-deficient compounds and exist as polymeric structures in the solid state. This statement is correct.
$(B)$ $LiH$ is unreactive to oxygen at moderate temperatures,whereas it reacts at higher temperatures. This statement is correct.
$(C)$ Due to the small size and high polarizing power of $Be^{2+}$ and $Mg^{2+}$ ions,$BeH_2$ and $MgH_2$ possess significant covalent character. This statement is correct.
$(D)$ The stability of alkali metal hydrides decreases as the size of the alkali metal cation increases down the group. Therefore,the correct order is $LiH > NaH > KH > RbH > CsH$. This statement is incorrect.
Thus,the correct statements are $(A)$,$(B)$,and $(C)$.

(D) $CuCl_{2}$ is a metal chloride that is soluble in water at room temperature.
$AgCl$ is known to be sparingly soluble in water at room temperature.
$PbCl_{2}$ is a metal chloride that is insoluble in cold water but soluble in hot water.
Therefore,the correct sequence is $x = CuCl_{2}$,$y = AgCl$,and $z = PbCl_{2}$.