Please wait...

Chemistry Test - 23
Result
Chemistry Test - 23
  • /

    Score
  • -

    Rank
Time Taken: -
  • Question 1/10
    1 / -0

    When water is added to an aqueous solution of an electrolyte, what is the change in specific conductivity of the electrolyte?

    Solutions

    Factors affecting electrolytic conductance are:

    Concentration of ions: The sole reason for the conductivity of electrolytes is the ions present in them. The conductivity of electrolytes increases with an increase in the concentration of ions as there will be more charge carriers if the concentration of ions is more and hence the conductivity of electrolytes will be high.

    Nature of electrolyte: Electrolytic conduction is significantly affected by the nature of electrolytes. The degree of dissociation of electrolytes determines the concentration of ions in the solution and hence the conductivity of electrolytes.

    Substances such as CH3COOH, with a small degree of separation, will have less number of ions in the solution and hence their conductivity will also below, and these are called weak electrolytes. Strong electrolytes such as

    KNO3 have a high degree of dissociation and hence their solutions have a high concentration of ions and so they are good electrolytic conductance.

    Temperature: Temperature affects the degree to which an electrolyte gets dissolved in solution. It has been seen that higher temperature enhances the solubility of electrolytes and hence the concentration of ions which results in an increased electrolytic conduction.

    When water is added to an aqueous solution the number of ions per unit volume decreases i.e., the concentration of ions decreases and hence thereby conductivity gets decreased.

  • Question 2/10
    1 / -0

    Which of the following is not formed when H2S reacts with acidic K2Cr2O7 solution?

    Solutions

    In the reaction of potassium dichromate with hydrogen sulphide in presence of an acidic medium of sulphuric acid, a redox reaction takes place as follows:

    During the reaction, the potassium chromate acts as the oxidizing agent, due to the presence of the hexavalent chromium in (+6) oxidation state. It is thus reduced to (+3) oxidation state.

    Then, the reduction half-cell reaction will be:

    Cr2O72+14H++6e2Cr3++7H2O

    Also, the sulphide S2 acting as the reducing agent, is oxidised to sulphur (S) in the reaction. Then, the oxidation half-cell reaction will be:

    S2S+2e

    Thus, combining the oxidation and reduction half-cell reaction, the balanced equation obtained is:

    K2Cr2O7+3H2 S+4H2SO43S+K2SO4+Cr2(SO4)3+7H2O

    The products formed are sulphur, potassium sulphate, chromium sulphate and water.

  • Question 3/10
    1 / -0

    Glycerol is:

    Solutions

    Glycerol is Trihydric alcohol.

    Compounds having one −OH group is called monohydric alcohol.

    Compounds having two −OH group is called dihydric alcohol.

    Compounds having three −OH group is called trihydric alcohol.

    Image of glycerol is given below, it has three −OH group

  • Question 4/10
    1 / -0

    In which of the following compounds manganese has an oxidation number equal to that of iodine in KIO4?

    Solutions

    We know that:

    Oxidation number of potassium, (K)=1

    And, Oxidation number of oxygen, (O)=2

    For KIO4:

    Let lodine has x oxidation number.

    1+x+4(2)=0

    x=81

    x=7

    For KMnO4:

    Let Mn hasaoxidation number.

    1+a+4(2)=0

    a=7

  • Question 5/10
    1 / -0

    Which of the following d-block element has half-filled penultimate as well as valence subshell?

    Solutions

  • Question 6/10
    1 / -0

    The given reaction is a:

    Solutions

    The given reaction is a1,4 addition reaction.

    In the first step, a molecule of HBr is added to a conjugated diene. Both H atom and Br atom are added to terminal C atoms. This is 1,4 addition or conjugate addition. In the next step, the reaction with Mg in presence of ether gives a Grignard reagent (RMgX) which then attacks a molecule of carbon dioxide. Acid hydrolysis gives carboxylic acid.

  • Question 7/10
    1 / -0

    Nitrobenzene on reaction with conc. HNO3/H2SO4 at 80100C forms which one of the following products?

    Solutions

    Mixture of [Conc HNO3 conc H2SO4] gives +NO2 which acts as electrophile and in nitrobenzene NO2 group is a meta directing group so nitronium ion attacks at meta position.

  • Question 8/10
    1 / -0

    The total number of alkenes possible by dehydrobromination of 3 -bromo-3cyclopentylhexane using alcoholic KOH is :

    Solutions

    Preparation of Alkenes from Alkyl Halides:

    Alkyl halides, upon heating with an alcoholic solution of potassium hydroxide, forms alkenes and halogen acids as by-products. This reaction is known as dehydrohalogenation.

    Since hydrogen is removed from β carbon, this reaction is also termed as β elimination.

    Saytzeff Rule

    In dehydrohalogenation reactions, the major product is alkene that has a maximum number of alkyl groups attached to doubly bonded carbon and other products are considered to be minor.

    Hence, the total number of alkenes formed is 5.

  • Question 9/10
    1 / -0

    Pick out the correct statement with respect to [Mn(CN)6]3:

    Solutions

    In the complex [Mn(CN)6]3, the oxidation state of Mn is +3. Mn3+ ion has d4 outer electronic configuration. It is an inner orbital complex. Inner d orbitals are used which results in d2sp3 hybridisation.

    So, the molecular geometry is octahedral.

  • Question 10/10
    1 / -0

    Solutions

    In the manufacturing of sulphuric acid, a step involves the reaction between SO2 and Oin the presence of platinized asbestos to give SO3.

    SO2 + O2 → SO3

    In the above reaction if the traces of arsenious oxide (As2O3) is used then it acts as a catalytic poison by decreasing the activity of the reaction.

User Profile
-

Correct (-)

Wrong (-)

Skipped (-)


  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
Get latest Exam Updates
& Study Material Alerts!
No, Thanks
Click on Allow to receive notifications
×
Open Now