Tag: chemistry

Questions Related to chemistry

For the reaction, $2{ N } _{ 2 }{ O } _{ 5 }\left( g \right) \longrightarrow 4N{ O } _{ 2 }\left( g \right) +{ O } _{ 2 }\left( g \right) $, if the concentration of $N{ O } _{ 2 }$ increases by $5.2\times { 10 }^{ -3 }M$ in $100$ sec, then the rate of reaction is:

chemistry reaction kinetics determining rates graphically calculating rate of reaction graphically rate of a chemical reaction

  1. $1.3\times { 10 }^{ -5 }M{ s }^{ -1 }$

  2. $5\times { 10 }^{ -4 }M{ s }^{ -1 }$

  3. $7.6\times { 10 }^{ -4 }M{ s }^{ -1 }$

  4. $2\times { 10 }^{ -3 }M{ s }^{ -1 }$

  5. $2.5\times { 10 }^{ -5 }M{ s }^{ -1 }$

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Correct Option: A
Explanation:

$\vartheta =\cfrac { 1 }{ 4 } \cfrac { d }{ dt } [{ NO } _{ 2 }]=\cfrac { 1 }{ 4 } (5.2\times { 10 }^{ -5 }M{ s }^{ -1 })\ =1.3\times { 10 }^{ -5 }{ Ms }^{ -1 }$

A reaction is represented as $2A + B \mapsto  2C + 3D$. The concentration of C at 10 s is 4 moles $l^{-1}$. The concentration of C at 20 seconds is 5.2 moles $l^{-1}$. The rate of reaction of B in the same time interval could be :

chemistry reaction kinetics determining rates graphically calculating rate of reaction graphically rate of a chemical reaction

  1. $-0.12$ mole $l^{-1} S^{-1}$

  2. $-0.6$ mole $l^{-1} S^{-1}$

  3. $-0.06$ mole $l^{-1} S^{-1}$

  4. $-1.2$ mole $l^{-1} S^{-1}$

Show answer
Correct Option: C
Explanation:

$r _{B} = \dfrac{1}{2}\dfrac{\Delta C}{\Delta t}= \dfrac{-1}{2}\dfrac{(1.2)}{10}$


$(\Delta C= 5.2 -4 = 1.2, \Delta t= 10 sec.)$

$= -0.06$ mole l$^{-1}$ sec$^{-1}$
Hence the answer is $C$.

For $S{O _2}C{l _{2\left( g \right)}} \to S{O _{2\left( g \right)}} + C{l _{2\left( g \right)}},$ Pressures of $S{O _2}C{l _2}$ at $t = 0$ and $t = 20$ minutes respectively are $700mm$ and $350mm.$ When $\log \left( {{P _0}/p} \right)$ is plotted against time ($t$), slope equals to:

chemistry reaction kinetics determining rates graphically calculating rate of reaction graphically rate of a chemical reaction

  1. $1.505 \times {10^{ - 2}}{s^{ - 1}}$

  2. $1.202 \times {10^{ - 3}}{\min ^{ - 1}}$

  3. $1.505 \times {10^{ - 2}}{\min ^{ - 1}}$

  4. $0.3465\ {\min ^{ - 1}}$

Show answer
Correct Option: A
Explanation:

$k=\dfrac{2.303}{t}log\dfrac{P _0}{P}$ [1st order reaction]

Plot of $log\dfrac{P _0}{P}$ against $t$ will give slope $=  \dfrac{k}{2.303}$
Using given data, $k=\dfrac{2.303}{20}log \dfrac{700}{350}$
$\dfrac{k}{2.303}=\dfrac{log2}{20}=1.5\times 10^{-2}s^{-1}$
Slope $=1.5\times 10^{-2}s^{-1}$

From the concentrations of R at different times given below. Determine  the average rate of the reaction range: R $\rightarrow$ P in given intervals of time.

t (s) 0 5 10 20 30
$10^{-3}\, \times\, [R] \,(mol\, L^{-1})$ 160 80 40 10 2.5
chemistry reaction kinetics determining rates graphically calculating rate of reaction graphically rate of a chemical reaction

  1. $3.5\times\,10^{2}$ to $0.42 \, \times\, 10^{2}$ $mol.L^{-1}\, s^{1}$

  2. $7\times\,10^{2}$ to $0.84 \, \times\, 10^{2}$ $mol.L^{-1}\, s^{1}$

  3. $8\times\,10^{3}$ to $0.37 \, \times\, 10^{3}$ $mol.L^{-1}\, s^{1}$

  4. $16\times\,10^{3}$ to $0.75 \, \times\, 10^{3}$ $mol.L^{-1}\, s^{1}$

Show answer
Correct Option: D
Explanation:

Average Rate $=\cfrac{ change \ in \ concentration }{ change \ in \ time }$


$\therefore$ here we wanted to find reaction range

Initially avergae rate$=\cfrac{ (160-80) }{ (5-0) }=$$\cfrac{ 80 }{ 5 }$
$=16$

Here, ${ 10 }^{ 3 }$ already given.

$\therefore$ Average rate $=16 \times {10}^{3}\ mol {L}^{-1} {s}^{-1}$

Final average rate $=\cfrac{ (10-2.5) }{(30-20) }=\cfrac{ 7.5 }{ 10 }=0.75$

$\therefore$ Average Rate $=0.75 \times {10}^{3}\ mol {L}^{-1} {s}^{-1}$

Milk and water dissolve in each other. They are:

chemistry sorting materials into groups properties of materials grouping and classification of objects nature of things

  1. immiscible liquids

  2. solvent and solutions

  3. miscible liquids

  4. None of the above

Show answer
Correct Option: C
Explanation:

The two liquid which can dissolve in each other and make a homogenous mixture is called miscible liquid.

Milk and water are miscible liquids.

Option (C) is correct.

During the formation of rain, when water vapour changes back to liquid in the form of rain drops:

chemistry grouping of materials properties of materials grouping and classification of objects nature of things

  1. Heat is absorbed

  2. Heat is released

  3. Heat is first absorbed and then released

  4. There is no exchange of heat

Show answer
Correct Option: B
Explanation:

The energy contained in the gaseous form (vapour) is more than the energy contained in the liquid form (water). Therefore when vapour changes to water it loses some heat.

______ are the smallest unit of matter that can take part in a chemical reaction.

chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

  1. Molecules

  2. Compounds

  3. Atoms

  4. Electrons

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Correct Option: C
Explanation:

Dalton's atomic theory states that atoms are the smallest unit of matter that can participate in a chemical reaction. Chemical reactions involve the combination, separation, or rearrangement of atoms, but atoms are neither created, destroyed, divided into parts, or converted into atoms of any other kind.

Dalton's theory fails to determine the existence of

chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

  1. molecules

  2. compounds

  3. allotropes

  4. All of the above

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Correct Option: C
Explanation:

Dalton's atomic theory fails to explain the existence of allotropes; it does not account for differences in properties of charcoal, graphite, diamond.

According to Dalton, atoms of different elements combine with one another to form :

chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

  1. compounds

  2. elements

  3. solution

  4. All of the above

Show answer
Correct Option: A
Explanation:

 According to Dalton, atoms of different elements combine with one another to form compounds.

Dalton had suggested that an atom is indivisible. 

chemistry atoms, molecules and radicals history of atomic model atomic theory of dalton daltons atomic theory

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Dalton had suggested that an atom is indivisible. All matter is composed of elements, which in turn are made up of small indivisible particles called atoms.