Tag: chemistry

Questions Related to chemistry

Volatile nature of halogens is because:

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. halogen molecules are bonded by strong forces

  2. halogen molecules are bonded by electrostatic forces

  3. the forces existing between the discrete molecules are only weak Van der Waals forces

  4. halogen molecules are more reactive

Show answer
Correct Option: C
Explanation:

Van der Waals force- It is a general term used to define the attraction of intermolecular forces between molecules.

Van der Waals force $\propto$ Molecular weight
As you go down the group, halogens become less volatile, as their shell size increases. This increases the Van der Waals forces as there are more electrons, hence increasing the force of attraction between molecules. This makes them less volatile.

The element with highest electron affinity among the halogens is :

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. F

  2. $Cl$

  3. Br

  4. $I$

Show answer
Correct Option: B
Explanation:

As moving down the group electron affinity of elements decreases

But in case of $\textbf{Fluorine}$, it is a small atom with a small amount of space available in its 2p orbital. Because of this, any new electron trying to attach to fluorine experiences lower electron affinity from the electrons already living in the element's 2p orbital. Since chlorine's outermost orbital is a 3p orbital, there is more space, and the electrons in this orbital are inclined to share this space with an extra electron. Therefore, chlorine has a higher electron affinity than fluorine, and this orbital structure causes it to have the highest electron affinity of all of the elements.

Hence electron affinity of $\textbf{Chlorine}$ is higher in halogens.

Chlorine displaces the following from their salts :

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. Fluorine

  2. Nitrogen

  3. Bromine

  4. Iodine

Show answer
Correct Option: C,D
Explanation:

Chlorine displaces Bromines and Iodine from their salts as chlorine is more electronegative than bromine and iodine.
$2KBr+Cl _2\rightarrow 2KCl+Br _2$
$2KI+Cl _2\rightarrow 2KCl+I _2$

Which one of the following halogen liberates oxygen on reacting with $H _2O$ ?

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. $I _2$

  2. $Cl _2$

  3. $Br _2$

  4. $F _2$

Show answer
Correct Option: D
Explanation:

Reaction of $F _2$ and $H _2O$-

$F _2 + H _2O \longrightarrow 2HF + \dfrac{1}{2}O _2$
So $F _2$ liberates oxygen on reacting with $H _2O$

Which of the following non-metals sublimes on heating?

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. Fluorine

  2. Chlorine

  3. Bromine

  4. Iodine

Show answer
Correct Option: D
Explanation:

Iodine crystals sublime because though there are covalently bonded within the molecule holding two iodine atoms together, only Van der Waals' forces exist between the iodine molecules. Van der Waal's forces are very weak interactions between molecules of a substance hence the Iodine molecules can escape from the solid structure easily.

Which of the following halides is inert towards hydrolysis at room temperature? 

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. ${ SiCl } _{ 4 }$

  2. ${ PCl } _{ 3 }$

  3. ${ NCl } _{ 3 }$

  4. ${ NF } _{ 3 }$

Show answer
Correct Option: D
Explanation:
Hydrolysis takes place through the coordination with lone pair of electron of water molecule. But neither nitrogen, nor fluorine have vacant d-orbital for coordination. Hence $N{F} _{3}$ behaves as inert towards hydrolysis.

Elements in the halogen family belonging to 17th group in the periodic table show similarity in their properties .

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Similar properties:-

(i) Group 17 elements have high electronegativity than other groups.
(ii) They have high $e^-$ affinity than other groups.
(iii) Group 17 has high $e^-$ gain enthalpy.

The incorrect order is :

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. Thermal stability : $HF > HCl > HBr$

  2. Lewis basic character : $PF _3 < PCl _3 < PBr _3$

  3. $\%$ p-character : $NO^+ _2 > NO^- _3 > NH^+ _4$

  4. Bond angle : $NH _3 > PH _3 > AsH _3$

Show answer
Correct Option: C

Correct order of volatility is:

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. $HF > HCl > HBr > HI$

  2. $HCl > HBr > HI > HF$

  3. $HI > HBr > HCl > HF$

  4. $HBr < HCl < HI < HF$

Show answer
Correct Option: B
Explanation:

Volatility depends on intermolecular interactions of a compound, as molecular weight increases so do the Vander wals forces. So the expected order should be: $HF < HCl<HBr<HI$ but we must remember HF has hydrogen bonding and the extent of Hydrogen bonding is very high because of high electonegativity of fluorine and linear bonding. Hence HF is least volatile. The correct order is $HCl>HBr>HI >HF$.

Bromine is formed when concentrated $HBr$ is heated with ?

group 17 elements - trends in chemical properties group 17 elements - properties p- block elements-ii p-block elements chemistry

  1. $KMn{O} _{4}$

  2. ${K} _{2}{Cr} _{2}{O} _{7}$

  3. $Mn{O} _{2}$

  4. $All\ of\ these$

Show answer
Correct Option: A
Explanation:

When concentrated $HBr$ is heated with $KMnO _4$ then bromine is liberated.The reaction involved is $2KMnO _4+16HBr\longrightarrow 2MnBr _2=2KBr+8H _2O+5Br _2$