Chemistry · Textbook solutions

Elements of Group 1 and 2

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 31 questions

8. Elements of Group 1 and 2 — worked examples

8 q

Solved Examples

Worked · 8
  1. Solved Ex.8.1
    Justify the placement of hydrogen in the group of alkali metals with the help of reaction with halogens.
  2. Solved Ex.8.2
    Sodium forms ionic compounds having formulae NaCl\mathrm{NaCl}, NaH\mathrm{NaH} and Na2CO3\mathrm{Na_2CO_3}. Explain.
  3. Solved Ex.8.3
    Explain the observed values 496 kJ/mol and 737 kJ/mol of the first ionization enthalpies of Na and Mg, respectively.
  4. Solved Ex.8.4
    What is the oxidation state of Na in Na2O2\mathrm{Na_2O_2}?
  5. Solved Ex.8.5
    The atomic radii of Na, K and Mg are 186, 227 and 160 pm, respectively. Explain the differences.
  6. Solved Ex.8.6
    NaCl\mathrm{NaCl} is an ionic compound but LiCl\mathrm{LiCl} has some covalent character, explain.
  7. Solved Ex.8.7
    Magnesium strip slowly tarnishes on keeping in air but metallic calcium is readily attacked by air. Explain.
  8. Solved Ex.8.8
    Calculate % (by mass) of a H2O2\mathrm{H_2O_2} solution which is 45.4 volume.

Exercise

23 q

1. Explain the following

Practice · 6
  1. Explain the following
    Ex Q.1 (A)
    Hydrogen shows similarity with alkali metals as well as halogens.
  2. Ex Q.1 (B)
    Standard reduction potential of alkali metals have high negative values.
  3. Ex Q.1 (C)
    Alkaline earth metals have low values of electronegativity; which decrease down the group.
  4. Ex Q.1 (D)
    Sodium dissolves in liquid ammonia to form a solution which shows electrical conductivity.
  5. Ex Q.1 (E)
    BeCl2\mathrm{BeCl_2} is covalent while MgCl2\mathrm{MgCl_2} is ionic.
  6. Ex Q.1 (F)
    Lithium floats an water while sodium floats and catches fire when put in water.

2. Write balanced chemical equations for the following.

Practice · 4
  1. Write balanced chemical equations for the following.
    Ex Q.2 (A)
    CO2\mathrm{CO_2} is passed into concentrated solution of NaCl\mathrm{NaCl}, which is saturated with NH3\mathrm{NH_3}.
  2. Ex Q.2 (B)
    A 50% solution of sulphuric acid is subjected to electrolyte oxidation and the product is hydrolysed.
  3. Ex Q.2 (C)
    Magnesium is heated in air.
  4. Ex Q.2 (D)
    Beryllium oxide is treated separately with aqueous HCl\mathrm{HCl} and aqueous NaOH\mathrm{NaOH} solutions.

3. Answer the following questions

Practice · 4
  1. Answer the following questions
    Ex Q.3 (A)
    Describe the diagonal relationship between Li and Mg with the help of two illustrative properties.
  2. Ex Q.3 (B)
    Describe the industrial production of dihydrogen from steam. Also write the chemical reaction involved.
  3. Ex Q.3 (C)
    A water sample, which did not give lather with soap, was found to contain Ca(HCO3)2\mathrm{Ca(HCO_3)_2} and Mg(HCO3)2\mathrm{Mg(HCO_3)_2}. Which chemical will make this water give lather with soap? Explain with the help of chemical reactions.
  4. Ex Q.3 (D)
    Name the isotopes of hydrogen. Write their atomic composition schematically and explain which of these is radioactive ?

4. Name the following

Practice · 5
  1. Name the following
    Ex Q.4 (A)
    Alkali metal with smallest atom.
  2. Ex Q.4 (B)
    The most abundant element in the universe.
  3. Ex Q.4 (C)
    Radioactive alkali metal.
  4. Ex Q.4 (D)
    Ions having high concentration in cell sap.
  5. Ex Q.4 (E)
    A compound having hydrogen, aluminium and lithium as its constituent elements.

5. Choose the correct option.

Practice · 4
  1. Choose the correct option.
    Ex Q.5 (A)
    The unstable isotope of hydrogen is .....
    1. A.
      H-1
    2. B.
      H-2
    3. C.
      H-3
    4. D.
      H-4
  2. Ex Q.5 (B)
    Identify the odd one.
    1. A.
      Rb
    2. B.
      Ra
    3. C.
      Sr
    4. D.
      Be
  3. Ex Q.5 (C)
    Which of the following is Lewis acid ?
    1. A.
      BaCl2\mathrm{BaCl_2}
    2. B.
      KCl\mathrm{KCl}
    3. C.
      BeCl2\mathrm{BeCl_2}
    4. D.
      LiCl\mathrm{LiCl}
  4. Ex Q.5 (D)
    What happens when crystalline Na2CO3\mathrm{Na_2CO_3} is heated ?
    1. A.
      releases CO2\mathrm{CO_2}
    2. B.
      loses H2O\mathrm{H_2O}
    3. C.
      decomposes into NaHCO3\mathrm{NaHCO_3}
    4. D.
      colour changes.