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The p-Block Elements — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryThe p-Block Elements4 Marks
Question
Read the passage given below and answer the following questions:
Interhalogen compounds are formed when halogen group elements react with each other. These are the compounds which consist of two or more different elements of group$-17$. A halogen with large size and low electronegativity reacts with an element of group$-17$ with small size and high electronegativity. As the ratio of radius of larger and smaller halogen increases, the number of atoms in a molecule also increases.
The following questions are multiple choice questions. Choose the most appropriate answer:
  1. The stability of interhalogen compounds follows the order.
  1. $IF_3 > BrF_3 > CIF_3$
  2. $CIF_3 > BrF_3 > IF_3$
  3. $BrF_3 > IF_3 > CIF_3$
  4. $CIF_3 > IF_3 > BrF_3$
  1. Identify the correct match from the following.
  1. $[ICI_2]^- - $ bent.
  2. $IF_7 $- pentagonal bipyramidal.
  3. $CIF_3 $- trigonal planar.
  4. $[BrF_4]^-$ - square pyramidal.
  1. In $XA_5$, the central atom has $($both $X$ and $A$ are halogens$).$
  1. $5$ bond pairs and no lone pairs.
  2. $5$ bond pairs and one lone pair.
  3. $6$ bond pairs and no lone pairs.
  4. $4$ bond pairs and one lone pair.
  1. In the known interbalogen compounds, the maximum number of atoms are,
  1. $4$
  2. $5$
  3. $8$
  4. $7$
  1. Which of the following is not the characteristic of interhalogen compounds.
  1. They are more reactive than halogens.
  2. They are quite unstable but none of them is explosive.
  3. They are covalent in nature.
  4. They have low boiling points and are highly volatile.
✓

Answer

  1. (a) $IF_3 > BrF_3 > CIF_3$
Explanation:

Thermal stability decreases as the size difference or the electronegativity difference between the two halogen atoms decreases.
  1. (b) $IF_7 - $ pentagonal bipyramidal.
Explanation:

$[ICI_2]^- -$ linear, $CIF_3 - T-$shaped,

$[BrF_4]^- -$ Square planar.
  1. (b) 5 bond pairs and one lone pair.
Explanation:

It has square pyramidal shape and has 5 bond pairs and one lone pair.
  1. (c) $8$
Explanation:

In $IF_7,$ iodine is the least electronegative halogen, so its highest oxidation number $(+7)$ is more stable than those of the lighter member of the group.
  1. (d) They have low boiling points and are highly volatile.
Explanation:

Some interhalogens are solids and are not volatile.

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The halogen elements show great resemblances to one another in their chemical behaviour and properties of their compounds with other elements. There is, however, a progressive change in properties from F through $Cl, Br,$ and I to At. F is most reactive among the halogens and in fact, from all other elements and it has certain other properties that set it apart from the other halogens.
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  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
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  1. Assertion: Fluoride does not show oxidation number greater than zero.
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Read the passage given below and answer the following questions: An ideal solution may be defined as the solution which obeys Raoult's law exactly over the entire range of concentration. The solutions for which vapour pressure is either higher or lower than that predicted by Raoult's law are called non-ideal solutions.Non-ideal solutions can show either positive or negative deviations from Raoult's law depending on whether the A-B interactions in solution are stronger or weaker than A - A and B - B interactions. The following questions are multiple choice questions. Choose the most appropriate answer:
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  4. All of these.
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  1.  
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  1. Water-HCI mixture.
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  2. Forms minimum boiling azeotrope.
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In these questions (Q. No. i-iv), a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements, and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements, but reason is not correct explanation for assertion.
  3. Assertion is correct statement, but reason is wrong statement.
  4. Assertion is wrong statement, but reason is correct statement.
  1. Assertion: Molecular solids are characterized by low melting point.
Reason: Molecular solids are made up of covalent molecules.
  1. Assertion: Ionic solids are characterized by high melting and boiling point.
Reason: Ionic solids have coulombic forces of attraction between their ions.
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Reason: Covalent solids are constituted by ions.
  1. Assertion: Diamond and graphite do not have the same covalent structure.
Reason: Silicon carbide is typical example of network solid.
  1. Assertion: Covalent solids have high melting points.
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Read the passage given below and answer the following questions:
All the elements of group $16$ form hydrides: $H_2O, H_2S, H_2Se, H_2Te$ and $H_2Po.$ All these hydrides have angular structure which involves $sp^3$ hybridisation of the central atom. All hydrides are volatile. The volatility increases from $H_2O$ to $H_2S$ and then decreases. All hydrides are weakly acidic in character. The increase in acidic character from $H_2O$ to $H_2Te$ is a resultof thedecrease in the $1 H-E ($where$ E = O, S, Se, Te, Po)$ bond dissociation enthalpy from $H_2O$ to $H_2Te.$ All the hydrides except water are reducing agents. The reducing property of these hydrides increases from $H_2S$ to $H_2Te.$
In these questions $(Q.No. i - iv),$ a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
  1. Assertion: Water has high boiling point.
Reason: Water molecules are associated with hydrogen bonding.
  1. Assertion: $H_2Te$ has less acidic character than $H_2S.$
Reason: Bond dissociation enthalpy of $H-Te$ is less than $H-S.$
  1. Assertion: Reducing nature of hydrides of group-16 elements increases as the atomic number of central atom increases.
Reason: Due to strong force of attraction of $H-E$ bond.
  1. Assertion: $H_2O$ is the only hydrides of the chakogens which is liquid.
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  1. Assertion: The thermal stability of the hydrides decreases as: $H_2O > H_2S > H_2Se > H_2Te.$
Reason: Due to increase in the size of central atom on going down the group.
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$(a).$ Predict the expression for the rate of reaction and order for the following:
$H_2 + Br_2 \rightarrow 2 HBr$
What are the units of rate constant for the above reaction?
$(b).$ How will the rate of reaction be affected if the concentration of $Br_2$ is tripled?
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The following reaction, $\text{A}_{(\text{g})}\xrightarrow{\ \ \triangle\ \ \ }\text{P}_{(\text{g})}+\text{Q}_{(\text{g})}+\text{R}_{(\text{g})},$ follows first order kinetics. The half-life period of this reaction is $69.3s$ at $500^\circ C$. The gas A is enclosed in a container at $500^\circ C$ and at a pressure of $0.4$ atm.
The following questions are multiple choice questions. Choose the most appropriate answer:
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  1. $0.4s^{-1}$
  2. $0.02s^{-1}$
  3. $0.01s^{-1}$
  4. $0.3s^{-1}$
  1. The pressure of the gas $A$ after $230$ s will be:
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  2. $0.36$ atm
  3. $0.4$ atm
  4. $0.036$ atm
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  2. $1.12$ atm
  3. $0.4$ atm
  4. $3.08$ atm
  1. The plot ofln[A] vs twill be:
  1. Linear with slope $= k$
  2. Linear with intercept $= In[A]_0$
  3. Linear with slope $= In[A]_0$
  4. Linear with intercept $= [A]_0$
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  1. $\text{C}_2\text{H}_{4(\text{g})}+\text{H}_{2(\text{g})}\rightarrow\text{C}_2\text{H}_{6(\text{g})}$
  2. $2\text{N}_2\text{O}_{5(\text{g})}\rightarrow4\text{NO}_{2(\text{g})}+\text{O}_{2(\text{g})}$
  3. $2\text{N}\text{H}_{3(\text{g})}\xrightarrow[\triangle]{\text{pt}}\text{N}_{2(\text{g})}+3\text{H}_{2(\text{g})}$
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Read the passage given below and answer the following questions:
The adjective 'crystalline' when applied to solids, implies an ideal crystal in which the structural units, termed as unit cells, are repeated regularly and indefinitely in three dimensions in space. The unit cell, containing at least one molecule, has a definite orientation and shape defined by the translational vectors, a, b and c. The unit cell therefore has a definite volume, V that contains the atoms and molecules necessary for generating the crystal. Every crystal can be classified as a member of one of the seven possible crystal systems or crystal classes that are defined by the relationships between the individual dimensions, a, b and c of the unit cell and between the individual angles, ⁣$\alpha,\beta$ and $\gamma$ of the unit cell. The structure of the given crystal may be assigned to one of the $7$ crystal systems, to one of the $14$ Bravais lattices, and to one of the 230 space groups. These uniquely define the possible ways of arranging atoms in a three-dimensional solid. Based on these observations, seven crystal systems were identified: triclinic, monoclinic, trigonal or rhombohedral, tetragonal, hexagonal, rhombic or orthorhombic and cubic.
The following questions are multiple choice questions. Choose the most appropriate answer:
  1. The crystal system of a compound with unit cell dimensions, $a = 0.38$7nm, $b = 0.387$nm and $c = 0.504$nm $\alpha=\beta=90^\circ$ and $\gamma=120^\circ$ is.
  1. Cubic
  2. Hexagonal
  3. Orthorhombic
  4. Rhombohedral.
  1. The unit cell with the structure given below represents________________crystal system.
  1. Cubic
  2. Orthorhombic
  3. tetragonal
  4. trigonal
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  1. $\text{a}=\text{b}=\text{c},\ \alpha=\beta=\gamma\neq90^\circ$
  2. $\text{a}\neq\text{b}=\text{c},\ \alpha=\beta=\gamma=90^\circ$
  3. $\text{a}\neq\text{b}\neq\text{c},\ \alpha\neq\beta\neq\gamma\neq90^\circ$
  4. $\text{a}\neq\text{b}\neq\text{c},\ \alpha=\gamma=90^\circ\beta\neq90^\circ$
  1. The unit cell with dimensions $\alpha=\beta=\gamma=90^\circ,\ \text{a}=\text{b}\neq\text{c}$ is.
  1. Cubic
  2. Triclinic
  3. Hexagonal
  4. Tetragonal.
  1. An example of orthorhombic crystal system is.
  1. $SnO_2$
  2. $KN0_3$
  3. $ZnO$
  4. $K_2Cr_2O_7$
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