Chemistry (Test 2)

Tancet Anna University : Mechanical Engineering

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| Some Basic Concepts of Chemistry | | Structure of Atom | | Classification of Elements and Periodicity in Properties | | Chemical Bonding and Molecular Structure | | States of Matter | | Thermodynamics | | Equilibrium | | Redox Reactions | | Hydrogen | | The s-Block Elements | | The p-Block Elements | | Organic Chemistry Some Basic Principles and Techniques | | Hydrocarbons | | Environmental Chemistry | | Solid State | | Chemistry Solutions | | Electrochemistry | | Chemical Kinetics | | Surface Chemistry | | General Principles and Processes of Isolation of Elements | | The d- and f- Block Elements | | Coordination Compounds | | Haloalkanes and Haloarenes | | Alcohols Phenols and Ethers | | Aldehydes Ketones and Carboxylic Acids | | Organic compounds containing Nitrogen | | Biomolecules | | Polymers | | Chemistry in Everyday Life | | UNIT 1: Basic Concepts of Chemistry and Chemical Calculations | | UNIT 2: Quantum Mechanical Model of Atom | | UNIT 3: Periodic Classification Of Elements | | UNIT 4: Hydrogen | | UNIT 5: Alkali and Alkaline Earth Metals | | UNIT 6: Gaseous State | | UNIT 7: Thermodynamics | | Unit I: Metallurgy | | Unit II: p-Block Elements I | | Unit III: p-Block Elements II | | Unit IV: Transition and Inner Transition Elements | | Unit V: Coordination Chemistry | | Unit VI: Solid State | | Unit VII: Chemical Kinetics |
Q.1
A zero order reaction X →Product , with an initial concentration 0.02M has a half life of 10 min. if one starts with concentration 0.04M, then the half life is
A. 10 s
B. 5 min
C. 20 min
D. cannot be predicted using the given information
Answer : Option C
Explaination / Solution:




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Q.2
 This reaction follows first order kinetics. The rate constant at particular temperature is 2.303 × 102 hour1 . The initial concentration of cyclopropane is 0.25M.  What will be the concentration of cyclopropane after 1806 minutes? (log 2 = 0.3010)
A. 0.125M
B. 0.215M
C. 0.25 × 2.303M
D. 0.05M
Answer : Option B
Explaination / Solution:



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Q.3
If 75% of a first order reaction was completed in 60 minutes , 50% of the same reaction under the same conditions would be completed in
A. 20 minutes
B. 30 minutes
C. 35 minutes
D. 75 minutes
Answer : Option B
Explaination / Solution:

t75% = 2t50%

t50% = (t75% / 2) = (60/2) = 30 min


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Q.4
The number of unit cells in 8 gm of an element X ( atomic mass 40) which crystallizes in bcc pattern is (NA is the Avogadro number)
A. 6.023 X 1023
B. 6.023 X 1022
C. 60.23 X 1023
D. ( [6.023 x 1023 ] / [8 x 40] )
Answer : Option B
Explaination / Solution:

in bcc unit cell,

2 atoms ≡ 1 unit cell

Number of atoms in 8g of element is ,

Number of moles = 8g / 40 g mol−1 = 0.2 mol

1 mole contains 6.023 ×1023 atoms

0.2 mole contains 0.2 × 6.023 ×1023 atoms

( 1unit cell / 2 atoms ) × 0.2 × 6.023 × 1023

6.023 ×1022 unit cells


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Q.5
The yellow colour in NaCl crystal is due to
A. excitation of electrons in F centers
B. reflection of light from Cl- ion on the surface
C. refraction of light from Na+ ion
D. all of the above
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.6
An excess of silver nitrate is added to 100ml of a 0.01M solution of pentaaqua chloride chromium(III)chloride. The number of moles of AgCl precipitated would be
A. 0.02
B. 0.002
C. 0.01
D. 0.2
Answer : Option B
Explaination / Solution:

The complex is [M(H2O)5 Cl] Cl2

1000 ml of 1M solution of the complex gives 2 moles of Cl ions

1000 ml of 0.01M solution of the complex will give

[100 ml x 0.01M x 2Cl-] / [1000 ml x 1M] = 0.002 moles of C  ions


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Q.7
How many geometrical isomers are possible for [ Pt(Py)(NH3)(Br)(Cl)] ?
A. 3
B. 4
C. 0
D. 15
Answer : Option A
Explaination / Solution:

Three isomers. If we consider any one of the ligands as reference ( say Py), the arrangement  of other three ligands ( NH3, Br and Cl ) with respect to (Py) gives three geometrical isomers.


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Q.8
Which of the following d block element has half filled penultimate d sub shell as well as half filled valence sub shell?
A. Cr
B. Pd
C. Pt
D. none of these
Answer : Option A
Explaination / Solution:

Cr [Ar] 3d5 4s1

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Q.9
Which of the following statements is not true?
A. on passing H2S, through acidified K2Cr2O7 solution, a milky colour is observed.
B. Na2Cr2O7 is preferred over K2Cr2O7 in volumetric analysis
C. K2Cr2O7 solution in acidic medium is orange in colour
D. K2Cr2O7 solution becomes yellow on increasing the PH beyond 7
Answer : Option B
Explaination / Solution:
No Explaination.


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Q.10

Assertion : Ce4+ is used as an oxidizing agent in volumetric analysis.

Reason: Ce4+ has the tendency of attaining +3 oxidation state.
A. Both assertion and reason are true and reason is the correct explanation of assertion.
B. Both assertion and reason are true but reason is not the correct explanation of assertion.
C. Assertion is true but reason is false.
D. Both assertion and reason are false.
Answer : Option A
Explaination / Solution:
No Explaination.


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