cbse 11th chemistry | Online Objective Test

Organic Chemistry Some Basic Principles and Techniques Prepare / Learn

Q1. Aniline is separated from aniline-water mixture using following technique:

A. Differential extraction

B. Steam distillation.

C. Chromatography

D. Fractional distillation

Answer : Option B
Explaination / Solution:

Steam distillation is a special type of distillation(separation process) for temperature sensitive materials like natural aromatic compounds.It was a popular laboratory method for purification of organic compounds..

States of Matter Prepare / Learn

Q2. The van der Waals Equation adjusts the measured volume

A. down by subtracting a factor from the entire container volume that accounts for the molecular volume

B. up by subtracting a factor from the entire container volume that accounts for the molecular volume

C. up by subtracting a factor from the entire container volume that accounts for the container volume

D. down by adding a factor from the entire container volume that accounts for the molecular volume

Answer : Option A
Explaination / Solution:

nb is subtracted.

Equilibrium Prepare / Learn

Q3.

What will be the correct order of vapour pressure of water, acetone and ether At

3 0^{\circ} C

. Given that among these compounds, water has maximum boiling point and ether has minimum boiling point?

A. Water < ether < acetone

B. Acetone < ether < water

C. Water < acetone < ether

D. Ether < acetone < water

Answer : Option A
Explaination / Solution:

Water has maximum boiling point due to hydrogen bonding so its vapour pressure will be least because of low boiling point less amount of water will move to vapour phase at a particulat temperature so lesser will be the vapour pressure.

Redox Reactions Prepare / Learn

Q4.

Using the standard electrode potential of redox couples given below find out which of the following is the strongest oxidising agent.

E0 values: Fe3+/Fe2+ = +0.77; I2/I-(s) = +0.54; Cu2+/Cu = +0.34; Ag+/Ag = +0.80

A. Fe3+

B. Ag+

C. Cu2+

D. I2(s)

Answer : Option B
Explaination / Solution:

The more positive the value of E0, the greater is the tendency of the species to get reduced, therefore Ag+/Ag = +0.80 is strongest oxidising agent.

Some Basic Concepts of Chemistry Prepare / Learn

Q5.

Choose the most appropriate option to complete the statement -

" Whenever there is a rearrangement of atoms which makes or breaks chemical bonds ------------------------ "

A. catalysts are produced.

B. products appear,

C. reactants disappear

D. a chemical reaction takes place

Answer : Option D
Explaination / Solution:

The occurance of a chemical reaction is always associated with breaking & formation of bonds of the reactant and products along with rearrangement of their atoms , hence the statement at option 1 is most appropriate. ie. " Whenever there is a rearrangement of atoms which makes or breaks chemical bonds a chemical reaction takes place."

Hydrocarbons Prepare / Learn

Q6. Ozonolysis of an organic compound 'A' produces an equimolar mixture of acetone and propionaldehyde . Identify the organic compound 'A' .

A. 2 - Methyl - 2 - pentene

B. 2 - Pentene

C. 2 - Methyl - 1 - pentene

D. 1 - Pentene

Answer : Option A
Explaination / Solution:

2- Methyl -2 - pentene when treated with ozone forms an unstable ozonide intermediate . The ozonide when treated with $(z i n c - d u s t + H_{2} O)$ yields an aldehyde (propionaldehyde ) and a ketone ( acetone ) as the final products The conversion reactions are represented as below.

Thus , the compound A is (2-Methyl -2 -pentene )

Classification of Elements and Periodicity in Properties Prepare / Learn

Q7. Which one of the following molecules represents the increasing order of bond length ?

A. F2 < Cl2 < O2 < N2

B. Cl2 < O2 < N2 < F2

C. N2 < O2 < F2< Cl2

D. F2 < N2 < Cl2< O2

Answer : Option C
Explaination / Solution:

The bond lengths depend upon the number and type of bonds present in a molecule . Greater the number of bonds shorter would be the bond length.

Thus , the given molecules are all diatomic molecules where ,

(i) $N_{2}$ has the smallest bond length as it is triple bonded.

(ii) $O_{2}$ is double bonded so its bond length is greater than $N_{2}$ .

(iii) $F_{2} a n d C l_{2}$ both , though single bonded , the bond length of $C l_{2}$ is greater than that of $F_{2}$ due to its larger atomic size.

Hence , the correct increasing order of given molecules is $N_{2} < O_{2} < F_{2} < C l_{2}$

Structure of Atom Prepare / Learn

Q8.

Find energy of the photons which correspond to light of frequency $3 \times 10^{15}$ Hz (Hint: h = Planck’s constant = 6.626 × $10^{- 34}$ Js)

A. 0.988 ×

10^{- 18}

B. 2.988 ×

10^{- 18}

C. 1.308 ×

10^{- 18}

D. 1.988 ×

10^{- 18}

Answer : Option D
Explaination / Solution:

We know Planck's equation is

$E = h ν$

where E is energy, h is Planck’s constant, and $ν$ is frequency.

Put given values,

E = $6.626 \times 10^{- 34} \times 3 \times 10^{15}$ $= 1.988 \times 10^{- 18} J$

Environmental Chemistry Prepare / Learn

Q9. The greenhouse effect is thought to be the cause of:

A. An increase in asthma sufferers

B. An increase in global temperature

C. Skin cancer

D. Huge tomatoes

Answer : Option B
Explaination / Solution:

The greenhouse effect increases the global temperature

Hydrogen Prepare / Learn

Q10. The three isotopes of hydrogen in terms of chemical properties show one of the following properties

A. difference is in their rates of reactions

B. same rates of reactions because of the same electronic configuration

C. same rates of reactions because of the same mass

D. same rates of reactions because of the same enthalpy of bond dissociation

Answer : Option A
Explaination / Solution:

There are three isotopes of hydrogen namely, protium 1H1, deuterium 1H2 or D and lastly tritium 1H3 or T.

Out of these three isotopes of hydrogen, only tritium is radioactive in nature which emits low energy b particles. As the electronic configuration of isotopes is same, they all have similar chemical properties. But they have a difference in their rates of reaction, this happens because of the different bond disassociation enthalpies.

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