Tag: chemistry

Questions Related to chemistry

Which of the following forms a white precipitate when added to a solution of $NaCl$?

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. $N _2$

  2. $KI$

  3. $CCl _4$

  4. $AgNO _3$

  5. $CaCO _3$

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Correct Option: D
Explanation:

Silver nitrate $\displaystyle AgNO _3$ forms a white precipitate of $AgCl$ when added to a solution of $NaCl$. 

$\displaystyle AgNO _3 + NaCl \rightarrow AgCl \uparrow + NaNO _3$

What is the key element in soil fertilizer?

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. Carbon

  2. Nitrogen

  3. Oxygen

  4. Neon

  5. Argon

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Correct Option: B
Explanation:

Nitrogen is the key element in soil fertilizer. It is essential for plant growth but plants cannot utilize atmospheric nitrogen as it is inert due to presence of triple bond. Hence, it is supplied through fertilizer.

Which of the following releases a gas with the addition of dilute acid?

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. $N _2$

  2. $Kl$

  3. $CCl _4$

  4. $AgNO _3$

  5. $CaCO _3$

Show answer
Correct Option: E
Explanation:

$\displaystyle CaCO _3 + 2HCl \rightarrow CaCl _2 + H _2O + CO _2 \uparrow$
Thus, calcium carbonate reacts with $HCl$ to form carbon dioxide gas.

Which of the following statements regarding nitrogen sesquioxide is not correct?

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. Nitrogen sesquioxide is stable only in the liquid state. It dissociated in the vapour phase

  2. Dinitrogen sesquioxide is a neutral oxide

  3. Dinitrogen sesquioxide contains a weak $N - N$ bond

  4. Dinitrogen sesquioxide exists in two different crystalline forms

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Correct Option: B
Explanation:
Nitrogen sesquioxide or dinitrogen trioxide $(N _2O _3)$ is an acidic oxide. It is an anhydride of nitrous acid and dissolves in water to form $HNO _2$, an unstable acid.

$N _2O _3 + H _2O \rightarrow 2HNO _2$

Which of the following is the density of nitrogen at STP?

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. $0.33g/L$

  2. $0.65g/L$

  3. $0.80g/L$

  4. $1.25g/L$

  5. $1.60g/L$

Show answer
Correct Option: D
Explanation:

At STP, one mole of any gas occupies 22.4litres of volume. Nitrogen exists in molecular form as $N _2$. 

So, $Denisty= \dfrac{\text Molecular \ mass}{\text Volume}$

Here a Molecular mass of one mole of $N _2$. is 14(2)=28 grams and Volume is 22.4 litres.
So $Denisty= \dfrac{28}{22.4}g/L = 1.25g/L$.
Option D is correct

Which of the following gas, when ignited, burns with a blue flame and is not very soluble in water?

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. $O _2$

  2. $CO _2$

  3. $N _2$

  4. $He$

Show answer
Correct Option: C
Explanation:
Nitrogen when ignited in presence of oxygen it forms various oxides of nitrogen like $NO,\ NO _2$ and burns with a blue flame.
Hence, option $C$ is correct.

Which of the following element occurs in free form in nature?

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. $N$

  2. $P$

  3. $As$

  4. $Sb$

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Correct Option: A
Explanation:

Nitrogen occurs in the free state as $N _2$ as it has less size it has more tendency to from pi bonds with same elements and get stability.
Hence option  A is correct.

$2N 2+O _2 \longrightarrow $ _________ ?

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. $N _2O$

  2. $NO _2$

  3. $NO$

  4. $N _2O _2$

Show answer
Correct Option: A
Explanation:

Nitrogen and oxygen react to form nitrous oxide.


$2N _2 + O _2 \rightarrow 2N _2O$

${ N } _{ 2 }(g)\ +\ { 3H } _{ 2 }(g)\rightleftharpoons { 2NH } _{ 3 }(g)$


For the reaction initially the mole was 1 : 3 of $N _2$ and ${ H } _{ 2 }$. At equilibrium 50% of each has reacted. If the equilibrium pressure is p, the partial pressure of ${ NH } _{ 3 }$ at equilibrium is :

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. $\dfrac { p }{ 3 }$

  2. $\dfrac { p }{ 4 }$

  3. $\dfrac { p }{ 6 }$

  4. $\dfrac { p }{ 8 }$

Show answer
Correct Option: A
Explanation:
$N _2 + 3H _2⇌2NH _3$
  1           3             0
(1-$x$)  ($3-3x$)     $2x$
            
$1-x =  \dfrac{1}{2}$
$\therefore x=\dfrac{1}{2}$
Mole of $H _2 = $ 1.5 mol
Mole of $N _2 = $ 0.5 mol
Mole of $NH _3 = $ 1.0 mol
Now,
Mole fraction of $NH _3$ =$\dfrac{1}{3}$

partial pressure = $p*\dfrac{1}{3}=\dfrac{p}{3}$

Gas B is paramagnetic and support the combustion compound B is :

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. $N _2$

  2. $N _2O$

  3. $O _2$

  4. $Na _2O$

Show answer
Correct Option: C
Explanation:

$O _2$ is paramagnetic due to the presence of $2$ unpaired $e^-$ in the $\Pi$-antibonding orbital.

$\sigma1s^2\sigma^*1s^2\sigma2s^2\sigma^*2s^2\sigma2p _3^2\Pi2p _x^2=\Pi2p _y^2\Pi^*2p _x^1=\Pi^*2p _y^1$
Also, $O _2$ supports combustion as it does not burn but it is an oxidizer, it oxidizes other reactive materials, itself getting reduced.