Tag: chemistry

Questions Related to chemistry

Which of the following is a state function and also an extensive property?

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. Internal energy

  2. Pressure

  3. Molar heat capacity

  4. Temperature

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Correct Option: A
Explanation:

$\Delta E=nCv\Delta T$ (depend on n)

Which of the following is not a thermodynamic state function?

chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

  1. Work

  2. Internal energy

  3. Free energy

  4. Temperature

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Correct Option: A
Explanation:

Work depend as path, so it is a path function.

Most abundant element in the earth's crust is:

chemistry general principles and processes of isolation of elements introduction to non-metals occurence of metals occurrence of metals and non metals

  1. Hydrogen

  2. Oxygen

  3. Aluminium

  4. Silicon

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Correct Option: B
Explanation:

Percentage abundance of the given elements in the earth's crust is :


Hydrogen - 0.14%
Oxygen - 46.6%
Aluminium - 8.1%
Silicon - 27.7% 

Therefore option B, oxygen is correct.

On heating a mixture of $NH _{4}Cl$ and $KNO _{2}$, we get:

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $NH _{4}NO _{3}$

  2. $KNH _{4}(NO _{3}) _{2}$

  3. $N _{2}$

  4. $NO$

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Correct Option: C
Explanation:

On heating mixture of $NH _4Cl$ and $KNO _2$, $N _2$ is obtained with potassium chloride and water.

$NH _4Cl+KNO _2\longrightarrow N _2+KCl+2H _2O$

On heating ammonium dichromate and barium azide separately we get:

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $N _{2}$ in both cases

  2. $N _{2}$ with ammonium dichromate and $NO$ with barium azide

  3. $N _{2}O$ with ammonium dichromate and $N _{2}$ with barium azide

  4. $N _{2}O$ with ammonium dichromate and $NO _{2}$ with barium azide

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Correct Option: A
Explanation:

On heating ammonium dichromate and barium azide separately we get $N _2$ in both cases.

$(NH _4) _2Cr _2O _7 \rightarrow Cr _2O _3 + 4H _2O +N _2$.

$Ba(N _3) _2 \rightarrow Ba + 3N _2$.

Hence option A is correct.

Concentrated nitric acid on reacting with any metal like copper releases gas with an irritating odour :

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $H _2 S$

  2. $CuS$

  3. $H _2$

  4. $NO _2$

Show answer
Correct Option: D
Explanation:

Nitrogen dioxide is the chemical compound with the formula $NO _2$. It is one of several nitrogen oxides. $NO _2$ is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent air pollutant. Reduction of concentrated nitric acid by metal (such as copper).
$4 HNO _3 +Cu \rightarrow Cu(NO _3) _2+ 2 NO _2 + 2 H _2O$

Nitrogen is liberated by the thermal decomposition of :

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $NH _4NO _2$

  2. $NaN _3$

  3. $(NH _4) _2Cr _2O _7$

  4. All of these

Show answer
Correct Option: D
Explanation:

$ { { (NH } _{ 2 }) } _{ 2 }{ Cr } _{ 2 }{ O } _{ 7 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } { Cr } _{ 2 }{ O } _{ 3 }+{ N } _{ 2 }+4{ H } _{ 2 }O\ N{ H } _{ 4 }{ NO } _{ 2 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } { N } _{ 2 }+2{ H } _{ 2 }O\ 2{ NaN } _{ 3 }\xrightarrow [ thermal\quad decomposition ]{ \Delta  } 2Na+3{ N } _{ 2 } $

Hence, all of these. 

Out of the following which does not liberate $N _2$ gas on heating?

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $NaNO _2+NH _4Cl$

  2. $Ba(N _3) _2$

  3. $O _3+NO$

  4. $(NH _4) _2Cr _2O _7$

Show answer
Correct Option: C
Explanation:

A. $NaNO _2+NH _4Cl\longrightarrow N _2+2H _2O+NaCl$

B. $Ba(N _3) _2\longrightarrow Ba+3N _2$
C. $O _3+NO\longrightarrow NO _2+O _2$
D. $(NH _4) _2Cr _2O _7 \longrightarrow N _2+Cr _2O _3+4H _2O$
Hence, answer is $O _3+NO$..

Among the following compounds, which on heating do not produce ${ N } _{ 2 }$?

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. ${ \left( { NH } _{ 4 } \right) } _{ 2 }{ Cr } _{ 2 }{ O } _{ 7 }$

  2. ${ NH } _{ 4 }CI+Na{ NO } _{ 2 }$

  3. ${ NH } _{ 4 }CI+CaO$

  4. $Ba{ \left( { N } _{ 3 } \right) } _{ 2 }$

Show answer
Correct Option: C
Explanation:

The reaction is given by,

$2 NH _4Cl + CaO → 2 NH _3 + CaCl _2 + H _2O$

20 ml of mixture of $N _{2}$ and $CH _{4}$ was exploded with excess of air. There is contraction of 5 ml in volume after treatment with KOH solution, what is the percentage of $N _{2}$ in the mixture?($N _{2}$ is inert)

chemistry preparation of gases nitrogen gas component of air - nitrogen nitrogen

  1. $25%$

  2. $50%$

  3. $87.5%$

  4. $80%$

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Correct Option: C