Tag: chemistry

Questions Related to chemistry

In metallurgy of iron, limestone provides flux for removing impurities as slag.

chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

  1. True

  2. False

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Correct Option: A
Explanation:

The above statement is true.
In agglomeration and separation of melted or smelted copper it is necessary to introduce iron oxide or limestone as flux to remove the impurities.

Which has a lowest electron affinity among the following?

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. I

  2. Br

  3. Cl

  4. F

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Correct Option: A
Explanation:

Down the group $e^-$ affinity decreases due to increase in size. Here $I$ having large size has least $e^-$ affinity.

The electronic configuration of four atoms are given in brackets:
L : ($1s^2\,2s^2\,2p^1$);                    M : ($1s^2\,2s^2\,2p^5$);

Q : ($1s^2\,2s^2\,2p^6\,3s^1$);             R : ($1s^2\,2s^2\,2p^2$).

The element that would most readily form a diatomic molecule is :

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. Q

  2. M

  3. R

  4. L

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Correct Option: B
Explanation:

From the electronic configuration given it is clear that element M is 1 short of octet configuration. It belongs to group 17. Group 17 elements exist as diatomic molecules.


So, correct option is B.

Which is the correct arrangement of the compounds based on their bond strength?

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. HF > HCl > HBr > HI

  2. HI>HBr>HCl>HF

  3. HCl>HF>HBr>HI

  4. HF>HBr>HCl>HI

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Correct Option: A
Explanation:

Because electronegativity decreases down the group thereby $e^-$ attracting tendency decreases down the group. $F$ with high electronegativity will have strongest bond and $I$ with least electronegativity will have least bond strength.

Mark the correct statements about halogens.

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. Electron affinity of halogens is in the order F > Cl > Br > I.

  2. HF is the strongest hydrohalic acid.

  3. $F _{2}$ has lower bond dissociation energy than $Cl _{2}$.

  4. All halogens show variable oxidation states.

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Correct Option: C
Explanation:

$F _2$ has lower bond dissociation energy than $Cl _2$ due to its small size and high electronegativity.

The property of halogens which is not correctly matched is:

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. F>Cl>Br>I (Ionisation energy)

  2. F>Cl>Br>I (Electronegativity)

  3. I>Br>Cl>F (Density)

  4. F>Cl>Br>I (Electron affinity)

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Correct Option: D
Explanation:

$e^-$ affinity of $F$ is less than that of $Cl$ because of the small size and high electronegativity of $F$ it repels the incoming $e^-$ thereby decreasing its $e^-$ affinity whereas $Cl$ having bigger size than $F$ & can accommodate the new incoming extra $e^-$.

Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy? 

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. $HF$

  2. $HCl$

  3. $HBr$

  4. $HI$

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Correct Option: A
Explanation:
As the size of the halogen atom decreases the bond length between halogen and hydrogen decreases ,So the bond becomes stronger and hence the energy required to break the bond ( bond dissociation enthaphy) increases.

So the compound with highest bond dissociation energy is $HF$

Hence option A is correct.

Match the column I with column II and mark the appropriate choice.

Column I Column II
(A) $H _{2}SO _{4}$ (i) Highest electron gain enthalpy
(B) $CCl _{3}NO _{2}$ (ii)Chalcogen
(C) $Cl _{2}$ (iii) Tear gas
(D) Sulphur (iv) Storage batteries
chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. (A) $\rightarrow$ (iv), (B) $\rightarrow$ (iii), (C) $\rightarrow$ (i), (D) $\rightarrow$ (ii)

  2. (A) $\rightarrow$ (iii), (B) $\rightarrow$ (iv), (C) $\rightarrow$ (i), (D) $\rightarrow$ (ii)

  3. (A) $\rightarrow$ (iv), (B) $\rightarrow$ (i), (C) $\rightarrow$ (ii), (D) $\rightarrow$ (iii)

  4. (A) $\rightarrow$ (ii), (B) $\rightarrow$ (i), (C) $\rightarrow$ (iii), (D) $\rightarrow$ (iv)

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Correct Option: A
Explanation:

$H _2SO _4$ is used in storage batteries.

$CCl _3NO _2$ is chloropicrrin which is known as tear gas.
$Cl$ is the element of highest electron gain enthalpy.
Sulfur is the element belongs to 16th group which are also called as Chalcogens.
So the given data matches with option A.
Hence option A is correct.

Which one of these group off elements is also called the halogen family?

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. Group 16

  2. Group 18

  3. Group 10

  4. Group 17

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Correct Option: D
Explanation:

Group 17 is also called halogen family.

Less ionic compound among the following

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. NaF

  2. KCl

  3. KF

  4. NaCl

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Correct Option: A