Tag: chemistry

Questions Related to chemistry

Iodine deficiency in diet is ____.

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

  1. Solutions of iodine in KI are used in treatment of Goiter.

  2. Goiter is enlargement of thyroid gland.


  3. Iodine deficiency in diet is known to cause Goiter.

  4. Iodine is necessary for normal functioning of the thyroid gland.

Show answer
Correct Option: A,B,C,D
Explanation:
Iodine is necessary for normal functioning of the thyroid gland.
Iodine deficiency in diet is known to cause Goiter.
Goiter is enlargement of thyroid gland.
Solutions of iodine in KI are used in treatment of Goiter.

Which of the following will displace the halogen from the solution of of halide
a $) Br _{2}$ added to an $NaCl$ solution
$\mathrm{b}) Cl _{2}$ added to a $KBr$ solution
$\mathrm{c}) Cl _{2}$ added to an $NaF$ solution
$\mathrm{d}) Br _{2}$ added to to a $KI$ solution
Find the correct answer :

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

  1. a, b, c

  2. b, c

  3. b, d

  4. all are correct

Show answer
Correct Option: C
Explanation:

$Br^{-}$ can reduce $Cl _{2}$ to $Cl^{-}$ $(E _{cell}=+ve)$

$I^{-}$ can reduce $Br _{2}$ to $Br^{-}$ $(E _{cell}=+ve)$

$E _{cell}=+ve$ in both case

$\therefore$ Reaction is feasible

Iodine can be obtained from NaI solution by the action of:

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

  1. chlorine

  2. bromine

  3. soluble chloride

  4. soluble bromine

Show answer
Correct Option: A,B
Explanation:

The iodine can be obtained by reacting chlorine or bromine by NaI. This is because the electronegativity of chlorine and bromine is more than the iodine and also the reactivity of chlorine and bromine is more than the iodine.

Which of the following is incorrect?

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

  1. iodine is a solid

  2. chlorine is insoluble in water

  3. iodine is more reactive than bromine

  4. bromine is more reactive than chlorine

Show answer
Correct Option: B,C,D
Explanation:

Reactivity order:-
$F _2>Cl _2> Br _2>I _2$
Thus, chlorine is more reactive than bromine and bromine is more reactive than iodine.

Chlorine is soluble in water.

In KI solution, $ I _2 $ readily dissolves and forms :

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

  1. $ I^{-}$

  2. $ KI _2 $

  3. $ KI _2^- $

  4. $ KI _3 $

Show answer
Correct Option: D
Explanation:

In KI solution, $I _2$ readily dissolves and forms $KI _3$ which contains polyhalide ion $I _3^-$


$KI + I _2  \rightarrow KI _3$

Due to this, iodine is partly soluble in water but highly soluble in the $KI$ solution.

So, the correct option is $D$

Correct order of reactivity of halogens is:

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

  1. $I _2 > Br _2 > Cl _2 > F _2$

  2. $Br _2 > I _2 > Cl _2 > F _2$

  3. $Cl _2 > Br _2 > I _2 > F _2$

  4. $F _2 > Cl _2 > Br _2 > I _2$

Show answer
Correct Option: D
Explanation:

The reactivity of halogens decreases with increase in atomic number of halogens. So the correct order of reactivity of halogens is $F _2 > Cl _2 > Br _2 > I _2.$

Iodide of MilIon's base is :

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

  1. $HIO _3$

  2. $K _2Hgl _4$

  3. $NH _2HgO.HgI $

  4. $Hg(NH _2)I$

Show answer
Correct Option: C
Explanation:

Iodide of MilIon's base is $\displaystyle NH _2HgO.HgI$
It is formed when Nessler's reagent (alkaline solution of $\displaystyle K _2[HgI _4]$) reacts with $NH _3$. 

Iodide of MilIon's base is a reddish brown ppt.

Which two of the following salts are used for preparing iodized salt?
$(i)   KIO _3$
$(ii)  KI$
$(iii)  I _2$
$(iv)  HI$

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

  1. $(i)$ and $(ii)$

  2. $(i)$ and $(iii)$

  3. $(ii)$ and $(iv)$

  4. $(iii)$ and $(iv)$

Show answer
Correct Option: A
Explanation:
Iodised salt is table salt mixed with a small amount of various salts of the element iodine.
$KIO _3$ and $KI$ are used for preparing iodised salt.
Potassium iodate and potassium iodine is used in the iodized salt to prevent the iodine deficiency.

Iodine exists in which form in iodised salt.

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

  1. $I _2$

  2. $NaIO _3$

  3. $ICl$

  4. $IO^- _4$

Show answer
Correct Option: B
Explanation:

Iodised salt is table salt mixed with a minute amount of one of the four iodine containing salts of hydroiodic acid or iodic acid: potassium iodate or potassium iodine and sodium iodate or sodium iodide.

Assertion: Iodine is more soluble in water than in carbon tetrachloride.
Reason: Iodineis a polar compound.

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

  1. If both assertion and reason are true and the reason is a correct explanation of the assertion.

  2. If both assertion and reason are true but reason is not a correct explanation of the assertion.

  3. If the assertion is true but reason is false

  4. If both the assertion and reason are false

  5. If the assertion is false but the reason is true

Show answer
Correct Option: D
Explanation:

Iodine is less soluble in water than in carbon tetrachloride. Iodine is a non polar compound.
Iodine, being a non-polar compound is more soluble in $CCl _4$ (non-polar compound) than in water because "like dissolve like". So both the assertion and reason are false.