Self Studies

Chemistry Test - 8

Result Self Studies

Chemistry Test - 8
  • Score

    -

    out of -
  • Rank

    -

    out of -
TIME Taken - -
Self Studies

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Self Studies Self Studies
Weekly Quiz Competition
  • Question 1
    1 / -0

    Atoms of two elements P and Q have \(5\) electrons in \(2^{\text {nd }}\) shell and \(3^{\text {rd }}\) shell respectively. What will be the atomic numbers of these elements?

    Solution

    P has \(5\) electrons in the second shell \((n=2)\), thus the electronic configuration is: \(2,5\) and atomic number \(=7\) 

    Q has \(5\) electrons in the third shell \(({n}=3)\), thus the electronic configuration is: \(2,8,5\) and atomic number \(=15\).

    Geometrical Representation

  • Question 2
    1 / -0

    A segment of DNA has \(120\) adenine and \(120\) cytosine bases. The total number of nucleotides present in the segment is _________.

    Solution

    DNA has a double-stranded structure that is helical in orientation.In a DNA strand, the nucleotides are arranged in a manner that adenine is always paired with thymine and cytosine is always paired with guanine. Adenine and thymine are joined by two hydrogen bonds and guanine and cytosine are always joined by three hydrogen bonds.The Chargaff’s rule of base pairs states that the base pairs are present in a one to one ratio in a DNA segment. According to this, if there are \(120\) adenine, there have to be \(120\) thymines also present. If there are \(120\) cytosines, there should be \(120\) guanines also present. So there will be \(480\) nucleotides present in the given segment.

  • Question 3
    1 / -0

    Which of the following is easily controlled synthetic polymer reactions, not like free radical reactions?

    Solution

    Condensation polymerisation is easily controlled synthetic polymer reactions, not like free radical reactions.

    The most common reactions of synthetic polymers are esterification formation of ester linkages and amidation formation of amide linkages. Condensation reactions are easily controlled reactions, unlike free radical reactions. The easiness of control is that it can be stopped by adding the required agents.

  • Question 4
    1 / -0

    In the nitration of benzene, the active nitrating agent is:

    Solution

    Benzene and other aromatic compounds show characteristic electrophilic substitution reactions.

    In this reaction, a hydrogen atom of the aromatic ring is substituted by an electrophile.

    The substitution takes place by addition- elimination mechanism.

    Mechanism:

    • In the first step, the benzene ring donates pi electrons to the electrophile.
    • One of the carbon atoms forms a bond with the electrophile.
    • In the second step, the complex formed then loses a proton from the saturated carbon atom with the help of a base.
    • The aromatic ring is finally regenerated in the last step.

    Nitration of benzene:

    • Nitric acid and sulfuric acid used in nitration generate nitronium NO2+ ion as electrophiles.
    • Nitronium NO2+ is the nitrating agent.
    • The electrophile then attacks the benzene ring forming a sigma complex.
    • The σ complex is resonance stabilized.
    • The complex then loses a proton to form nitrobenzene.
    • The mechanism is shown as follows.

    So, as a mixture of sulfuric and nitric acid forms an electrophile, the reaction proceeds via electrophilic substitution and the nitrating agent is the nitronium ion NO2+​.

  • Question 5
    1 / -0

    Intermediate product of hydrolysis of cyanide is:

    Solution
    Intermediate product of hydrolysis of cyanide is \(\mathrm{RCONH}_{2}\) as shown in below given reaction:

     

  • Question 6
    1 / -0

    DNA is composed of repeating units of:

    Solution

    The full form of DNA is deoxyribonucleic acid which is an organic compound that has a unique molecular structure. It is present in all prokaryotic cells as well as eukaryotic cells. DNA is composed of repeating units of deoxyribonucleotides.Each DNA strand comprises repeating nucleotides. Each nucleotide has phosphate and also sugar that is a pentose group attached lengthwise and a nitrogenous base (Adenine, Guanine, cytosine and thymine) attached to the sugar.

    A nucleotide is the basic building block of nucleic acids. RNA and DNA are polymers that are made up of long chains of nucleotides.

  • Question 7
    1 / -0

    Phenols are more acidic than alcohols. This Is due to one the following reasons. Identify that.acidic

    Solution

    Phenols are more acidic than alcohols due to phenoxide ions being much better stabilized than alkoxide ions.

    Phenols react with aqueous sodium hydroxide to produce phenoxide ions. This indicates that the acidity of phenols is higher in comparison to the alcohols. The phenoxide ion is stabilized by the delocalization of the negative charge due to the resonance in the benzene ring.

  • Question 8
    1 / -0

    The enthalpy change of a reaction does not depend on:

    Solution

    The enthalpy change of a reaction does not depend on different intermediate reactions.

    Enthalpy change is a state function so it does not depend on the path taken by the reaction. it depends only on the difference of final and initial values of enthalpy change.

  • Question 9
    1 / -0

    Electrolysis of dilute aqueous \(NaCl\) solution was carried out by passing \(10\) milli ampere current. The time required to liberate \(0.01\) mol of \(H_{2}\) gas at the cathode is: (\(1\) Faraday \(=96500 Cmol ^{-1}\))

    Solution

    \(Q = i \times t\)

    \(Q =10 \times 10^{-3} \times t\)

    \(2 H_{2} O+2 e^{-} \rightarrow H_{2}+2 O H^{-}\)

    To liberate \(0.01\) mole of \(H_{2}\), \(0.02\) Faraday charge is required

    \(Q=0.02 \times 96500 C\)

    \(\therefore 0.02 \times 96500=10^{-2} \times t\)

    \(\Rightarrow t=19.3 \times 10^{4}\) sec

  • Question 10
    1 / -0

    Which one of the following is a primary standard?

    Solution

    Potassium dichromateis a primary standard.

    • The primary standard is a compound of sufficient purity from which standard solutions of known normalities can be prepared by direct weighing of it and diluting to a defined volume of solution.
    • Potassium Dichromate \(\left(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\right)\) is suitable to be used as a primary standard. It cannot be obtained in very pure form. It readily reacts with any traces of organic material or any other reducing substance in water.
Self Studies
User
Question Analysis
  • Correct -

  • Wrong -

  • Skipped -

My Perfomance
  • Score

    -

    out of -
  • Rank

    -

    out of -
Re-Attempt Weekly Quiz Competition
Self Studies Get latest Exam Updates
& Study Material Alerts!
No, Thanks
Self Studies
Click on Allow to receive notifications
Allow Notification
Self Studies
Self Studies Self Studies
To enable notifications follow this 2 steps:
  • First Click on Secure Icon Self Studies
  • Second click on the toggle icon
Allow Notification
Get latest Exam Updates & FREE Study Material Alerts!
Self Studies ×
Open Now