Tag: chemistry

Questions Related to chemistry

Complete the given reaction :


${(NH _4)} _2Cr _2O _7  \longrightarrow$

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

  1.  $3N _2+ 4H _2O+ 2Cr _2O _3$

  2. $N _2+ 3H _2O+ Cr _2O _3$

  3. $N _2 + 4H _2O+ Cr _2O _3$

  4. $4N _2+ 4H _2O+ Cr _2O _3$

Show answer
Correct Option: C

Which of the following on heating will not evolve N$ _2$ gas?

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

  1. NH$ _{3}$ + NaNO$ _{2}$

  2. NH$ _{4}$Cl + NaNO$ _{2}$

  3. N$ _{2}$O + Cu

  4. (NH$ _{4}$)$ _{2}$Cr$ _{2}$O$ _{7}$

Show answer
Correct Option: A
Explanation:

The given reactions take place as:


$NH _3 + NaNO _2 \rightarrow NH _3NO _2 + Na$


$NH _4Cl + NaNO _2 \rightarrow N _2 + NaCl + 2H _2O$

$N _2O +Cu \rightarrow N _2 + CuO$

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



Hence, the reaction between ammonia and sodium nitrate do not evolve $N _2$ gas. 

Thus option A is the correct answer.

$Mg _3N _2 \xrightarrow{H _2O} A(gas) \xrightarrow[\triangle]{CuO} B + C(g) + H _2O$
$C(g)$ can be obtained by heating:

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

  1. $(NH _4) _2SO _4$

  2. $(NH _4) _2Cr _2O _7$

  3. $NH _4NO _3$

  4. $NH _4Cl$

Show answer
Correct Option: B
Explanation:

$Mg _3N _2 \xrightarrow []{3H _2O} \underset {(A)}{2NH _3}+3MgO$

$NH _3 \xrightarrow []{CuO} \underset {(C)}{N _2}(g)+\underset {(B)}{Cu}+H _2O$
$N _2$ will be obtained by decomposition of Ammonium dichromate.
$(NH _4) _2Cr _2O _7 (s) \longrightarrow Cr _2O _3(g)+\underset {(C)}{N _2}+4H _2O$ .

Pure ${N} _{2}$ gas is obtained from:

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

  1. $NH _3 +  NaNO _2$

  2. $Ba(N _{3}) _{2}$

  3. $N _2O + Cu$

  4. $(NH _4) _2Cr _2O _7$

Show answer
Correct Option: B
Explanation:

Heating $Ba(N _3) _2$ we get pure $N _2$


$Ba(N _{3} ) _{2} \rightarrow Ba + 3N _{2} $

Hence, option B is correct.

Which of the following compounds does not give $N _2$ when heated?

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

  1. $NH _4NO _2$

  2. $NH _4NO _3$

  3. $NaN _3$

  4. Both A and B

Show answer
Correct Option: B
Explanation:

$(1)NH _4NO _2\overset{\Delta }{\rightarrow}N _2+2H _2O$
$(2)NH _4NO _3\overset{\Delta }{\rightarrow}N _2O+2H _2O$
$(3)2NaN _3\overset{\Delta }{\rightarrow}3N _2+2Na$

What is obtained when ammonium dichromate is heated?

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

  1. Nitrogen

  2. Oxygen

  3. Ammonia

  4. None of the above

Show answer
Correct Option: A
Explanation:

$(NH _4) _2 Cr _2O _7 \overset{\Delta}{\rightarrow}N _2 + 4H _2O+Cr _2O _3$

Pure $N _2$ gas is obtained from:

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

  1. $NH _3+NaNO _2$

  2. $NH _4Cl+NaNO _2$

  3. $N _2O+Ca$

  4. $(NH _4) _2Cr _2O _7$

Show answer
Correct Option: B
Explanation:

Pure $N _2$ gas is obtained when $NH _4Cl+ NaNO _2$ is reacted.

$NH _4Cl+ NaNO _2\rightarrow N _2 + 2 H _2O + NaCl$

Hence option B is correct.

Pure $N {2}$ can be obtained by heating_______.

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

  1. $NH _{3}$ with $CuO$

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

  3. $(NH _{4}) _{2}Cr _{2}O _{7}$

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

Show answer
Correct Option: D
Explanation:

Barium azide can also be used in the preparation of extra pure nitrogen on heating.
$Ba(N _3) _2 \rightarrow Ba + 3N _2$

$NH _4NO _3$ and $NH _4NO _2$ on heating decomposes into :

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

  1. $NO _2, N _2$

  2. $NO _2, NO _3$

  3. $N _2O, N _2$

  4. $NO _3, NO _2$

Show answer
Correct Option: C
Explanation:

Reaction:
$NH _4NO _3\overset{\triangle}{\longrightarrow} N _2O + 2H _2O$
$NH _4NO _2 \overset{\triangle}{\longrightarrow} N _2 + 2H _2O$

In the reaction,

${ \left( { NH } _{ 4 } \right)  } _{ 2 }{ Cr } _{ 2 }{ O } _{ 7 }\xrightarrow [  ]{ \Delta  } { N } _{ 2 }+{ H } _{ 2 }O+{ Cr } _{ 2 }{ O } _{ 3 }$

The coefficient of ${H} _{2}O$ is :

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

  1. $1$

  2. $2$

  3. $3$

  4. $4$

Show answer
Correct Option: D
Explanation:

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


To balance the reaction we require 4 moles of $H _2O$.

Hence option D is correct.