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Chemistry Test 222
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Chemistry Test 222
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  • Question 1/10
    4 / -1

     To balance the oxygen atom in the given reaction in acidic medium

    Cr2O72- (aq) → Cr3+(aq)  we

    Solutions

    As it is given that this reaction is in acidic medium, that means we have H+ on the reactant side so to balance Oxygen we have to add water on the product side instead of adding just Oxygen.

     

  • Question 2/10
    4 / -1

    Hydrogen gas is not liberated when the following metal is added to dil. HCl.

    Solutions

    The metals, present below hydrogen in the electrochemical series, cannot liberate hydrogen from the dilute acids.

    Among the given metals only Ag is present below hydrogen in electrochemical series, so it does not evolve hydrogen with dil HCl.

    Ag−IdilHCl ⟶ No reaction

     

  • Question 3/10
    4 / -1

    On the basis of the following E° values, the strongest oxidizing agent is :

    Solutions

    For the strongest oxidizing agent, the oxidizing potential should be least. Here, the oxidizing potential of Fe+2 is less than that of [Fe(CN)6​]4−. Therefore, Fe+2 is stronger oxidizing agent than [Fe(CN)6​]4−. Also, the stronger oxidizing agent should easily reduce itself. Here, Fe+3 is easily reduced than Fe+2. Therefore, among all the four, Fe+3 is the stronger oxidizing agent.

     

  • Question 4/10
    4 / -1

    Solutions

    Option A is correct.

    log10Kp = 8 - 6400/T.

    Convert temperature: T = 527 °C = 527 + 273 = 800 K.

    Substitute T = 800 K into the formula: log10Kp = 8 - 6400/800 = 8 - 8 = 0.

    Therefore Kp = 100 = 1.

    For an equilibrium that involves only pure solids and CO2(g), the activities of solids are unity, so Kp = pCO2 (with pressure in atm). Hence pCO2 = 1 atm, matching option A.

     

  • Question 5/10
    4 / -1

    A buffer solution is prepared in which the concentration of NH3 is 0.30M and the concentration of NH4+ is 0.20 M. If the equilibrium constant, Kb for NH3 equals 1.8 × 10–5, what is the pH of this solution ? (log 2.7 = 0.433).

    Solutions

     

  • Question 6/10
    4 / -1

    When an aqueous solution of H2SO4 is electrolysed, the ion discharged at anode is-

    Solutions

    Electrolysis of H2SO4

    Cathode:-

    2H+  +  2e-  -  H2    (Reduction)

    Anode:-

    4OH-  -  2H2O  +  O2  + 4e-  (Oxidation)

    OHions discharged at anode.

     

  • Question 7/10
    4 / -1

    the oxidation number of sulphur in S8,S2F2,H2S respectively are

    Solutions

    (i) Oxidation state of element in its free state is zero.

    (ii) Sum of oxidation states of all atoms in compound is zero.

    O.N of S in S8=0;    O.N of S in S2F2=+1

    O.N of S in H2S = -2

     

  • Question 8/10
    4 / -1

    Which one of the following molecular hydrides acts as a Lewis acid?

    Solutions

    Boron in B2H6 is electron deficient

     

  • Question 9/10
    4 / -1

    The reduction potential of an element A is -2.71V. What can be concluded from this?

    Solutions

    Reduction potential means to accept electrons to reduce oneself.

     A + e- → A- ∆Ereduction = +ve value

    Since, the reduction potential is negative, it means that the reaction will reverse to make ∆E value +ve. So the reaction becomes,

    A → A+ + e- 

    This becomes oxidation of A. So oxidation of A will be easy.

     

  • Question 10/10
    4 / -1

    Which of the following statements best describes the meaning of equilibrium in a chemical reaction?

    Solutions

    The correct answer is Option B - A state where the concentrations of reactants and products remain constant with time

    This describes a dynamic equilibrium in a closed system, where forward and reverse changes continue but balance each other.

    At equilibrium the rates of the forward and reverse reactions are equal, and as a result the concentrations remain constant with time.

    Equilibrium does not mean the reactions have stopped; microscopic conversion of reactants to products and products to reactants continues, but with no net change in concentrations.

    The amounts of reactants and products at equilibrium are not necessarily equal; their relative values depend on the equilibrium constant.

    Kc = [C]c[D]d / [A]a[B]b

    If Kc > 1, products are favored at equilibrium; if Kc < 1, reactants are favored. This shows equal concentrations are not required for equilibrium.

    Therefore, Option B is the correct description of chemical equilibrium.

     

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