14 th group elements (p-block) practice · Mixed difficulty

Option C is correct because Statement-1 is true (the C-O bond in CO+ is longer than in CO), and Statement-2 is false. When an electron is removed from CO to form CO+, it is removed from a bonding molecular orbital, which weakens the bond and increases the bond length.

Option D (Three dimensional network silicate) is correct because quartz (SiO2) has a three-dimensional network structure where each silicon atom is bonded to four oxygen atoms, and each oxygen atom is bonded to two silicon atoms.

Option C (Both are correct) is correct because six large chloride ions cannot be accommodated around the small $Si^{4+}$ ion, and the interaction between the lone pair of $Cl^-$ and $Si^{4+}$ is weak.

Option A (Pb and Sn) is correct because pewter is primarily an alloy of lead (Pb) and tin (Sn), although other metals may be added in small amounts.

Option A (Bi, Sn, Pb) is correct because Newton's alloy is a fusible alloy composed of bismuth (Bi), tin (Sn), and lead (Pb).

Option D ($\mathrm{P}{\mathrm{b}^{2 + }}$ salt) is correct because lead(II) chloride precipitates with HCl, dissolves on heating, and lead(II) sulfide precipitates with H2S in acidic solution.

Option C (Catenation tendency is higher in nitrogen when compared with other elements of the same group) is the wrong statement because nitrogen has a lower catenation tendency compared to other group 15 elements.

Option B ($\mathrm{P}{\mathrm{b}_3}{\mathrm{O}_4}$) is correct because minium is the common name for lead tetroxide, which has the formula $\mathrm{P}{\mathrm{b}_3}{\mathrm{O}_4}$.

Option B (Fullerene) is correct because fullerenes, such as $C_{60}$, are recently discovered allotropes of carbon.

Option A is correct because the C-F bond is the strongest due to the small size and high electronegativity of fluorine, making $CF_4$ thermally more stable.

The correct answer is B (${\mathrm{K}_2}\mathrm{O}.3\mathrm{A}{\mathrm{l}_2}{\mathrm{O}_3}.6\mathrm{Si}{\mathrm{O}_2}.2{\mathrm{H}_2}\mathrm{O}$) because this is the general chemical formula for mica.

Option B (Wood’s metal) is correct because Wood's metal is a low-melting alloy that melts at around 70°C, which is below the boiling point of water.

The correct answer is A ($\mathrm{S}{\mathrm{n}^{2 + }}$ is reducing while $\mathrm{P}{\mathrm{b}^{\mathrm{4 + }}}$ is oxidising) due to the inert pair effect.

The correct answer is D (Emission of sound while bending a tin rod) because "tin cry" is the characteristic sound produced due to the breaking of tin crystals when a tin rod is bent.

Option A (Galena) is correct because Galena is the principal ore of lead, chemically known as lead sulfide (PbS).

The correct answer is A (Carbon cannot expand its octet but silicon can expand) because silicon has available d-orbitals that allow it to expand its octet and accommodate more ligands, facilitating hydrolysis, while carbon does not.

Option C (For lead +2 , for tin +4) is correct because lead prefers the +2 oxidation state due to the inert pair effect, while tin prefers +4.

Option D is correct because in 3-D silicates, each $SiO_4$ unit shares all four corners with other tetrahedral units.

Option C (If Assertion is true but Reason is false) is correct because graphite is a good conductor, but it's due to delocalized electrons, not firmly held electrons.

Option D ($\mathrm{N}{\mathrm{a}_2}\mathrm{O}\mathrm{.CaO}.6\mathrm{Si}{\mathrm{O}_2}$) is correct because the common glass is primarily composed of sodium oxide (Na2O), calcium oxide (CaO), and silicon dioxide (SiO2) in approximately the given ratio.

Option C (Water gas is a mixture of water vapour and hydrogen) is false because water gas is a mixture of hydrogen and carbon monoxide, not water vapor and hydrogen.

Option C (CO2) is the correct answer because CO2 is a gaseous oxide formed by a group 14 element (carbon), it dissolves in water to form carbonic acid (decreasing pH), and the addition of group 2 hydroxides leads to the precipitation of carbonates.

Option D (${\mathrm{H}_2}\mathrm{S}$) is correct because hydrogen sulfide reacts with white lead paint to form lead sulfide, which is black.

Option A ($s{p^2}$) is correct because each carbon atom in fullerene is bonded to three other carbon atoms, resulting in $s{p^2}$ hybridization.

Option B (Acetic acid) is correct because acetic acid can corrode lead pipes due to the formation of lead acetate, which is soluble.

Option A (Metastannic acid) is correct because tin reacts with dilute nitric acid to form metastannic acid ($H_2SnO_3$) as the main product.

Option C is correct because at atmospheric pressure, solid CO2 undergoes sublimation, directly changing into a gas without forming a liquid phase, hence it doesn't wet the surface.

Option C (Refrigerant) is correct because solid CO2, also known as dry ice, is commonly used as a refrigerant due to its low temperature and sublimation properties.

Option D (formic acid with conc. $\mathrm{H}_2 \mathrm{SO}_4$) is correct because concentrated sulfuric acid acts as a dehydrating agent, removing water from formic acid to produce pure carbon monoxide.

Option B is correct because both the assertion and the reason are true, but the reason is not the correct explanation of the assertion. Nickel(II) compounds are thermodynamically more stable than platinum(II), and platinum(IV) compounds are relatively more stable than nickel(IV) compounds, but the latter does not explain the former.