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Rohit ChavanEduRev Class 9 |
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Rohit Chavan
EduRev Class 9
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Discussed Questions
The fluorescence life time of a molecule in solution is 10 ns. If the fluorescence quantum yield is 0.1, the rate constant of fluorescence decay is: - a)1 × 109 s–1
- b)1× 108 s–1
- c)1× 107 s–1
- d)9× 107 s–1
Correct answer is option 'C'. Can you explain this answer?
The fluorescence life time of a molecule in solution is 10 ns. If the fluorescence quantum yield is 0.1, the rate constant of fluorescence decay is:
a)
1 × 109 s–1
b)
1× 108 s–1
c)
1× 107 s–1
d)
9× 107 s–1
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Sanya Poswal answered • Apr 05, 2019 |
Rate of a reaction = dA/dt
So =0.1/10*10^(-9) sec -1 = 10^7 sec-1
And Quantum yield is the ratio of no of molecules consumed by no of photons absorbed
So =0.1/10*10^(-9) sec -1 = 10^7 sec-1
And Quantum yield is the ratio of no of molecules consumed by no of photons absorbed
100 ml of unknown reducing agent is reacted with 500 mL, 0.1 M excess I2 solution. If remaining I2 required 0.1 M, 200 mL Na2S2O3 solution for complete neutralization. Calculate normality of unknown reducing agent.
Correct answer is '0.8'. Can you explain this answer?
100 ml of unknown reducing agent is reacted with 500 mL, 0.1 M excess I2 solution. If remaining I2 required 0.1 M, 200 mL Na2S2O3 solution for complete neutralization. Calculate normality of unknown reducing agent.
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Sanya Poswal answered • Apr 05, 2019 |
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Sanya Poswal asked • Feb 05, 2019 |
Match the compounds in Column I with their characteristic test(s)/reaction(s) given in Column II. Indicate your answer by darkening the appropriate bubbles of the 4 × 4 matrix given in the ORS. [IIT 2008]Column I(A) 
(B) 
(C) 
(D) 
Column II
(P) sodium fusion extract of the compound gives Prussian blue colour with FeSO4 (Q) gives positive FeCl3 test
(R) gives white precipitate with AgNO3(S) reacts with aldehydes to form the corresponding hydrazone derivative... more
Match the compounds in Column I with their characteristic test(s)/reaction(s) given in Column II. Indicate your answer by darkening the appropriate bubbles of the 4 × 4 matrix given in the ORS. [IIT 2008]
Column I
(A)
(B)
(C)
(D)
Column II
(P) sodium fusion extract of the compound gives Prussian blue colour with FeSO4
(Q) gives positive FeCl3 test
(R) gives white precipitate with AgNO3
(R) gives white precipitate with AgNO3
(S) reacts with aldehydes to form the corresponding hydrazone derivative
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Roshni Chavan answered |
Ans.
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Sanya Poswal upvoted • Feb 05, 2019 |
Which of the following acids has the smallest dissociation constant? [IIT 2002]- a)CH3CHFCOOH
- b)FCH2CH2COOH
- c)BrCH2CH2COOH
- d)CH3CHBrCOOH
Correct answer is option 'C'. Can you explain this answer?
Which of the following acids has the smallest dissociation constant? [IIT 2002]
a)
CH3CHFCOOH
b)
FCH2CH2COOH
c)
BrCH2CH2COOH
d)
CH3CHBrCOOH
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Ankit Pal answered |
Jisme H+ dene k baad anion less stablize ho uska dissociation constt kam hoga or option c m Br ka -I bhi kam h or postion bhi jayada h to isliye iska sbse kam hoga ....
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Sanya Poswal upvoted • Feb 01, 2019 |
Toxicity of cadmium and mercury in the body in being reversed by proteins, mainly using the amino acid residue: - a)Glycine
- b)Leucine
- c)Lysine
- d)Cysteine
Correct answer is option 'D'. Can you explain this answer?
Toxicity of cadmium and mercury in the body in being reversed by proteins, mainly using the amino acid residue:
a)
Glycine
b)
Leucine
c)
Lysine
d)
Cysteine
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Bhoomika Sharma answered |
Cysteine contain sulphur and Cd and Hg are highly philic to sulphur... so cysteine binds Hg and Cd and hence their toxicity decreases.
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Sanya Poswal upvoted • Jan 29, 2019 |
Number of 1H NMR signals in the following compound is:
Correct answer is '5'. Can you explain this answer?
Number of 1H NMR signals in the following compound is:
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Shoaib Ali answered |
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Sanya Poswal upvoted • Jan 29, 2019 |
According to the equipartition principle of energy, the molar heat capacity at constant volume for CO2(g), SO2(g) and H2O(g) follows the trends:a)CO2 = SO2 = H2Ob)CO2 < SO2 = H2Oc)CO2 > SO2 = H2Od)CO2 = SO2 > H2OCorrect answer is option 'C'. Can you explain this answer?
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Vipin Singh answered |
Which of the following does not represent a phase diagram?- a)
- b)
- c)
- d)
Correct answer is option 'B'. Can you explain this answer?
Which of the following does not represent a phase diagram?
a)
b)
c)
d)
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Sanya Poswal answered • Jan 29, 2019 |
Phase cannot be more than 3 in one component system but in B phase =4 (1,2,4,5)
So F =1-4+2 So F is negative.
So F =1-4+2 So F is negative.
It the radii of A+ and B– are 95 pm and 181 pm respectively, the coordination number of A+ will be?- a)12
- b)8
- c)6
- d)4
Correct answer is option 'C'. Can you explain this answer?
It the radii of A+ and B– are 95 pm and 181 pm respectively, the coordination number of A+ will be?
a)
12
b)
8
c)
6
d)
4
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Sanya Poswal answered • Jan 29, 2019 |
First find radius ratio = radius of cation /radius of anion
= 95/181 =0.52 this ratio is for octahedral
So CN =6
Octahedral ratio = 0.414-0.732
= 95/181 =0.52 this ratio is for octahedral
So CN =6
Octahedral ratio = 0.414-0.732
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Sanya Poswal asked • Jan 29, 2019 |
Charcoal (1 gram) of surface area 100 m2 per gram, absorbs 60 mg of acetic acid from an aqueous solution at 25°C and 1 atmosphere pressure. The number of moles of acetic acid adsorbed per cm2 of charcoal surface is:- a)10–2
- b)10–6
- c)10–5
- d)10–9
Correct answer is option 'D'. Can you explain this answer?
Charcoal (1 gram) of surface area 100 m2 per gram, absorbs 60 mg of acetic acid from an aqueous solution at 25°C and 1 atmosphere pressure. The number of moles of acetic acid adsorbed per cm2 of charcoal surface is:
a)
10–2
b)
10–6
c)
10–5
d)
10–9
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Subarna Roy answered |
Molar mass of acetic acid is 60 g.mole^-1
i.e. 60 g = (60×1000 mg) of acetic acid contains 1 mole
so, 60 mg of acetic acid contains [{1/(60×1000 mg)}×60mg] moles
= 10^-3 moles
Now, surface area of 100 m² per gram i.e. (100×10⁴) cm² per gram charcoal can adsorb 60 mg or 10^-3 moles of acetic acid
therefore, the number of moles of acetic acid adsorbed per c... more
i.e. 60 g = (60×1000 mg) of acetic acid contains 1 mole
so, 60 mg of acetic acid contains [{1/(60×1000 mg)}×60mg] moles
= 10^-3 moles
Now, surface area of 100 m² per gram i.e. (100×10⁴) cm² per gram charcoal can adsorb 60 mg or 10^-3 moles of acetic acid
therefore, the number of moles of acetic acid adsorbed per c... more
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Sanya Poswal asked • Jan 29, 2019 |
If the transport number of Na+ is 0.463 (dilute solution of NaCl in methanol), the transport number of H+ (dilute solution of HCI in methanol) is: (Given, 
(NaCl in methanol) = 96.9 ohm-1 cm2 mol-1 and (HCI in methanol) = 192 ohm-1 cm2mol–1)- a)0.27
- b)0.46
- c)0.54
- d)0.73
Correct answer is option 'D'. Can you explain this answer?
If the transport number of Na+ is 0.463 (dilute solution of NaCl in methanol), the transport number of H+ (dilute solution of HCI in methanol) is: (Given, (NaCl in methanol) = 96.9 ohm-1 cm2 mol-1 and (HCI in methanol) = 192 ohm-1 cm2mol–1)
(NaCl in methanol) = 96.9 ohm-1 cm2 mol-1 and (HCI in methanol) = 192 ohm-1 cm2mol–1)a)
0.27
b)
0.46
c)
0.54
d)
0.73
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Harihara Subramanian answered |
where h, π, m and α are constants. Then C is:|
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Sanya Poswal asked • Jan 29, 2019 |
The correct order of crystal field strength is:
(Given: en = ethylenediamine)- a)CI– < H2O < en < (η5 -C5H5)-
- b)H2O < CI- < (η5 -C5H5)- < en
- c)H2O < (η5 -C5H5)- < en < Cl-
- d)en < Cl- < H2O < (η5 -C5H5)-
Correct answer is option 'A'. Can you explain this answer?
The correct order of crystal field strength is:
(Given: en = ethylenediamine)
(Given: en = ethylenediamine)
a)
CI– < H2O < en < (η5 -C5H5)-
b)
H2O < CI- < (η5 -C5H5)- < en
c)
H2O < (η5 -C5H5)- < en < Cl-
d)
en < Cl- < H2O < (η5 -C5H5)-
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Garima Chavan answered |
The correct order of crystal field strength is option A: CI- < h2o="" />< en="" />< />
Explanation:
To determine the crystal field strength, we need to consider the ligands and their ability to generate a crystal field around the central metal ion. The ligands in this case are CI-, H2O, en (ethylenediamine), and (5-C5H5)- (cyclopentadienyl).
1. CI- (chloride ion):
C... more
Explanation:
To determine the crystal field strength, we need to consider the ligands and their ability to generate a crystal field around the central metal ion. The ligands in this case are CI-, H2O, en (ethylenediamine), and (5-C5H5)- (cyclopentadienyl).
1. CI- (chloride ion):
C... more
The number of a and b particle(s), generated in the following radioactive decay process, are:
- a)one α and two β particles
- b)two α and one β particles
- c)one α and four β particles
- d)no α and four β particles
Correct answer is option 'A'. Can you explain this answer?
The number of a and b particle(s), generated in the following radioactive decay process, are:
a)
one α and two β particles
b)
two α and one β particles
c)
one α and four β particles
d)
no α and four β particles
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Sanya Poswal answered • Jan 29, 2019 |
As mass no is decreased by 4 so only 1 alpha particle is generated. Atomic mass decreased by 2 by alpha particle and beta particle increase the atomic mass by 2. So atomic mass remain same. Thus only 1 alpha particle and 1 beta generated
Given 
which of the following statement is incorrect:- a)Mg will reduced both in Ni+2 and Al+3 to their respective metal.
- b)Mg will reduce only Al+3 to Al and not Ni+2 to Ni
- c)Al will reduce only Ni+2 to Ni and not Mg+2 to Mg
- d)Mg+2 solution can easily be stored in the aluminium vessel.
Correct answer is option 'B'. Can you explain this answer?
Given which of the following statement is incorrect:
which of the following statement is incorrect:a)
Mg will reduced both in Ni+2 and Al+3 to their respective metal.
b)
Mg will reduce only Al+3 to Al and not Ni+2 to Ni
c)
Al will reduce only Ni+2 to Ni and not Mg+2 to Mg
d)
Mg+2 solution can easily be stored in the aluminium vessel.
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Sanya Poswal answered • Jan 29, 2019 |
Since reduction potential of Mg2+ is - ve so, it is a good reducing agent and thus can easily reduce both Al3+, Ni2+ to their respective metal and Mg2 +itself get oxidize. So option b) is wrong
is 1.69 V & 
is 1.40 V, then 
will be(in Volt):
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Sanya Poswal asked • Jan 19, 2019 |
In a radioactive decay, an emitted electron comesfrom [1994]- a)The nucleus of atom
- b)The orbit with principal quantum number 1
- c)the inner orbital of the atom
- d)the outermost orbit of the atom.
Correct answer is option 'A'. Can you explain this answer?
In a radioactive decay, an emitted electron comesfrom [1994]
a)
The nucleus of atom
b)
The orbit with principal quantum number 1
c)
the inner orbital of the atom
d)
the outermost orbit of the atom.
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Sarthak Saini answered |
When a radioactive elements emits α or β
particle the new element formed may have
unstable nucleus. It may further disintegrate
by emitting α- or β particle forming a new
element. This process of integration may
continue till end product formed is a stable
compound.
particle the new element formed may have
unstable nucleus. It may further disintegrate
by emitting α- or β particle forming a new
element. This process of integration may
continue till end product formed is a stable
compound.
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Sanya Poswal asked • Jan 01, 2019 |
In a Steady flow process,a)heat transfer is constantb)The ratio of work transfer is constantc)The ratio of mass flow at inlet and outlet i... mored)All of theseCorrect answer is option 'D'. Can you explain this answer?
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Shounak Saini answered |
Steady flow process is a process where: the fluid properties can change from point to point in the control volume but remains the same at any fixed point during the whole process. A steady-flow process is characterized by the following:
- No properties within the control volume change with time. That is mcv = constant; Ecv = constant
- No properties change at the boundaries with time. Thus, the fluid properties at an inlet or exit will remain the same during the whole process.
- The heat and work interactions between a steady-flow system and its surroundings do not change with time.
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