The s-Block Elements

  • Question 213
    CBSEENCH11008305

    Which of the following compounds has the lowest melting point? 

    • CaBr2

    • CaI2

    • CaF2

    • CaCl2

    Solution

    B.

    CaI2

    As covalent character increases, melting point decreases, thus order of melting point is
    CaF2 > CaCl2 > CaBr2 > CaI2

    Question 214
    CBSEENCH11008317

    Which one of the following is present as an active ingredient in bleaching powder for bleaching action?

    • Ca(OCl)2

    • CaO2Cl

    • CaCl2

    • CaOCl2

    Solution

    D.

    CaOCl2

    CaOCl2, Calcium hypochlorite is the active ingredient in bleaching powder which releases chlorine.

    Question 215
    CBSEENCH11008321

    On heating which of the following releases CO2 most easily?

    • K2CO3

    • Na2CO3

    • MgCO3

    • CaCO3

    Solution

    C.

    MgCO3

    Order of thermal stability is 
    K2CO3 > Na2CO3 > CaCO3 > MgCO3
    Thus, MgCO3 releases CO2 most easily
    MgCO3 + heat ---> MgO + CO2

    Question 216
    CBSEENCH11008341

    What is the value of electron gain enthalpy of Na+ if IE1 of Na = 5.1 eV?

    • -5.1 eV

    • -10.2 eV

    • +2.55 eV

    • +10.2 eV

    Solution

    A.

    -5.1 eV

    IE1 of Na = - Electron gain enthalpy of Na+ ion.
     = -5.1 eV.

    NCERT Book Store

    NCERT Sample Papers

    Entrance Exams Preparation