Tag: properties of s block elements

Questions Related to properties of s block elements

Which of the following does not show the anomalous behaviour of Lithium?

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. Lithium reacts with nitrogen to form a nitride

  2. Lithium carbonate decomposes on heating

  3. Lithium nitrate gives $NO _2$ on heating

  4. Lithium is the strongest reducing agent

Show answer
Correct Option: D
Explanation:
Anomalous behavior of lithium is due to extremely small size of lithium. Its cation on account of small size and high nuclear charge, lithium exerts the greatest polarizing effect out of all alkali metals on the negative ion. Consequently, lithium ion possesses a remarkable tendency towards solvation and develops a covalent character in its compounds.

But lithium like other metals of the same group is a strong reducing agent. In fact, Lithium is the strongest reducing agent in aqueous solution.

Thus option D is correct.

The properties of $Li$ are similar to those of $Mg$. This is because:

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. both have nearly the same size.

  2. both has their charge to size ratio nearly the same.

  3. both have similar electronic configurations.

  4. both are found together in nature.

Show answer
Correct Option: B
Explanation:
  • The properties of lithium are similar to those of $Mg$ because they are having diagonal relationship.
  • The elements having diagonal relationship show similar properties and the reason is because the both of them will have similar electronegativity and polarising power i.e. charge per size ratio of both the elements are nearly the same.

Choose the correct answer form the alternatives given.
Which of the following statements is not true about alkali metals ?

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. All alkali metals from oxo salts such as carbonates, sulphates and nitrates.

  2. The basic character of oxides increases down the group.

  3. Carbonates and sulphates of lithium are stable and their stability decreases down the group.

  4. Solubility of carbonates and sulphates increases down the group.

Show answer
Correct Option: C
Explanation:
Characteristics of Alkali Metals-
  • Found in column 1A of the periodic table.
  • Have one electron in their outermost layer of electrons.
  • Easily ionized.
  • Silvery, soft, and not dense.
  • Low melting points.
  • Incredibly reactive.
  • They form oxo salts such as carbonates, sulphates and nitrates.
  • The basic character of oxides increases down the group.
  • The acidic character of oxides decreases down the group.
  • Solubility of carbonates and sulphates increases down the group.
  • As we move down the alkali metal group, the electropositive character increases. This causes an increase in the stability of alkali carbonates. However, lithium carbonate is not so stable to heat. This is because lithium carbonate is covalent.
  • Hence option C is not correct about alkali metals.

Choose the correct answer form the alternatives given.
Which of the following has lowest thermal stability?

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. $Li _2CO _3$

  2. $Na _2CO _3$

  3. $K _2CO _3$

  4. $Rb _2CO _3$

Show answer
Correct Option: A
Explanation:

Lithium carbonates are least thermal stable compound which decompose upon heating to give lithium oxide and carbon dioxide.
$ { Li } _{ 2 }C{ O } _{ 3 }\ \rightarrow {  Li } _{ 2 }O\ +\ C{ O } _{ 2 } $

Fill up the blanks with appropriate choices.
Lithium and magnesium react slowly with water. Their hydroxides are ________ soluble in water. Carbonates are Li and Mg ________ easily on heating. Both LiCl and $MgCl 2$ are _______ in entanol and are _____. They crystallise from their aqueous solutions as ______.

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. more, do not decompose, soluble, hygroscopic, hydrates

  2. less, decompose, soluble, deliquescent, hydrates

  3. freely, sublime, insoluble, deliquescent, anhydrous

  4. freely, decompose, soluble, hygroscopic, crystals

Show answer
Correct Option: B
Explanation:

A Diagonal Relationship is said to exist between certain pairs of diagonally adjacent elements in the second and third periods of the periodic table. These pairs (Li & Mg, Be & Al, B & Si etc.) exhibit similar properties.

Which of the following is used as a sources of hydrogen for filling of balloons that is convenient and can be carried around?

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. Lithium hydride

  2. Sodium borohydride

  3. Calcium metal

  4. Sodium formate

Show answer
Correct Option: A
Explanation:

  • LiH is produced by treating lithium metal with hydrogen gas.
  • It is used for filling meteorological balloons which carries instruments aloft to send back information on atmospheric pressure, temperature, humidity and wind speed by means of a small, expendable measuring device called a radiosonde
Hence option A is correct answer.

The solubility of metal halides depends on their nature, lattice enthalpy and hydration enthalpy of the individual ions. Amongst fluorides of alkali metals, the lowest solubility of LiF in water is due to:

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. ionic nature of lithium fluoride

  2. high lattice enthalpy

  3. high hydration enthalpy for lithium ion

  4. low ionisation enthalpy of lithium atom

Show answer
Correct Option: B
Explanation:

Lowest solubility of $LiF$ is due to high lattice enthalpy which is higher than hydration enthalpy. Hence, the dissociation of $Li-F$ bond becomes difficult.

$Li$ has an abnormal behaviour in its group, which is ____________.

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. lithium carbonate decomposes into its oxide on heating unlike other elements.

  2. $LiCl$ is covalent in nature.

  3. $Li _3N$ is a stable compound.

  4. $LiCl$ is a good conductor of electricity in the molten state.

Show answer
Correct Option: A,B,C
Explanation:

(A). Lithium carbonate, being less stable, decomposes into its oxide on heating, whereas other group IA carbonates are stable and do not decompose.


${ Li } _{ 2 }C{ O } _{ 3 }\ \underrightarrow { \triangle  } \ { Li } _{ 2 }O+C{ O } _{ 2 }$

(B). Lithium halides, except fluoride, are covalent due to fajan's rule.

(C) Lithium is the only 1A metal that can combine with inert nitrogen in air to form lithium nitride.

(D) Lithium chloride , like other alkali metals compounds , is a good conductor of electricity in molten state. 

Alkali metals readily react with oxyacids forming corresponding salts like ${ M } _{ 2 }{ CO } _{ 3 }$, ${ M }H{ CO } _{ 3 }$, ${ M }N{ O } _{ 3 }$, ${ M } _{ 2 }{ SO } _{ 4 }$, etc. with evolution of hydrogen. They also dissolve in liquid ${ NH } _{ 3 }$ but without the evolution of hydrogen. The color of its dilute solution is blue but when it is heated and concentrated then its color becomes bronze.

Which of the following statement about the sulphate of alkali metal is correct :

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. except ${ Li } _{ 2 }{ SO } _{ 4 }$ all sulphate of other alkali metals are soluble in water.

  2. all sulphates of alkali metals except lithium sulphate forms alum.

  3. the sulphates of alkali metals cannot be hydrolysed.

  4. all of these.

Show answer
Correct Option: D
Explanation:
Except ${ Li } _{ 2 }{ SO } _{ 4 }$ all sulphate of other alkali metals are soluble in water and forms alum. Thus, they form double salts with the sulphates of trivalent metals like $Al, Fe, Cr$ etc. The sulphates of alkali metals cannot be hydrolysed as they are salts of a strong acid and strong base. 

Which of the following statement(s) is/are true?

chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

  1. Both $LiCl$ and $MgCl _{2}$ are deliquescent.

  2. Lithium is least reactive but the strongest reducing agent amongst all the alkali metals.

  3. Liquid sodium metal is used as a coolant in fast breeder nuclear reactors.

  4. Lithium iodide is the most ionic in nature among all alkali metal halides.

Show answer
Correct Option: A,B,C
Explanation:

(A) $Li^{+}$ and $Mg^{2+}$ have higher polarising power and thus attract more number of water molecules.
(B) $Li$ is least reactive because of its highest ionisation energy on account of smaller size.
(C) It is one of the uses of liquid sodium as it has low melting point.
(D) $LiI$ is the most covalent due to smaller cation and bigger anion (according to Fajan's rule).