Tag: hydrogen and its compounds

Questions Related to hydrogen and its compounds

What is the trend of boiling points of hydrides of N, O, and F?

hydrides hydrogen and its compounds hydrogen chemistry

  1. Due to lower molecular masses $NH _{3}, H _{2}O$ and HF have lower boiling points than those of the subsequent group member hydrides

  2. Due to higher electronegativity of N, O and F; $NH _{3}, H _{2}O$ and HF show hydrogen bonding and hence higher boiling points than the hydrides of their subsequent group members.

  3. There is no regular trend in the boiling points of hydrides

  4. Due to higher oxidation states of N, O and F, the boiling points of $NH _{3}, H _{2}O$ and HF are higher than the hydrides of their subsequent group members.

Show answer
Correct Option: B
Explanation:

The boiling point increases with increase in molecular masses. But in the case of $N, O$ and $F$ they show the higher boiling point in molecules. 

This is due to the higher electronegativity of $N, O$ and $F$ which leads to hydrogen bonding in $NH _3, H _2O$ and $HF$ due to which the boiling point of these increases & is higher than the hydrides of their subsequent group members.

Which of the following hydrides is electron-precise hydride?

hydrides hydrogen and its compounds hydrogen chemistry

  1. $B _2H _6$

  2. $NH _3$

  3. $H _2O$

  4. $CH _4$

Show answer
Correct Option: D
Explanation:
Methane $CH _4$ is electron-precise hydride.
Diborane $B _2H _6$ is electron-deficient hydride
Ammonia $NH _3$ and water $H _2O$ are electron-rich hydrides.

Elements of group 14 form electron-precise (having required number of electrons to write the Lewis structure ) form precise hydrides.

Non-stoichiometric hydrides are produced by:

hydrides hydrogen and its compounds hydrogen chemistry

  1. palladium, vanadium

  2. manganese, lithium

  3. nitrogen, filorine

  4. carbon, nockel

Show answer
Correct Option: A
Explanation:

The hydrogen deficient compounds formed by the reaction of $d-block$ and $f-block$ elements with dihydrogen are called Non-stoichiometric compounds. 

The d-block and f-block element form non-stoichiometric hydride because of the vacant d- and f-orbitals along with the small size.
Their elemental composition proportions cannot be represented in integers. They disobey the law of constant composition. Among the elements given, only vanadium and palladium form non-stoichiometric hydrides.


Answer: (A) palladium, vanadium

From group 6 only one metal forms hydride. This metal is:

hydrides hydrogen and its compounds hydrogen chemistry

  1. Mo

  2. W

  3. Cr

  4. Co

Show answer
Correct Option: C
Explanation:

The low affinity of the elements of the group $6,7,8$ and $9$ towards hydrogen in their normal oxidation states prevent the formation of hydrides. This is called as hydride gap. 

In the group, $6$, Chromium $(Cr)$ is an exception as it is the only group $6$ element to form a hydride.

Answer: $(Cr)$

Only one element of ________ forms hydride. 

hydrides hydrogen and its compounds hydrogen chemistry

  1. group 6

  2. group 7

  3. group 8

  4. group 9

Show answer
Correct Option: A
Explanation:

The only element of group $6$ i.e. Chromium $(Cr)$ forms hydride. The other elements do not form hydride due to low affinity towards hydrogen.


Answer: (A) group $6$

Elements of which of the following group (s) of periodic table do not form hydrides?

hydrides hydrogen and its compounds hydrogen chemistry

  1. Groups 7, 8, 9

  2. Group 13

  3. Groups 15, 16, 17

  4. Group 14

Show answer
Correct Option: A
Explanation:

The elements of the groups $7,8,9$ show low affinity towards hydrogen due to which they lack the tendency to form hydrides.


Answer: (A) Groups $7,8,9$

Which of the following exists as associated molecules due to hydrogen bonding?

hydrides hydrogen and its compounds hydrogen chemistry

  1. $NH _{3}$

  2. $H _{2}O$

  3. $HF$

  4. $HCl$

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

Due to good extent of hydrogen bonding (hydrogen bonding is more favoured if the hydrogen is attached to an electronegative atom) in A, B and C options, they exist in chains or in groups attached through hydrogen bonding.

Match list I with list II. Choose the correct matching codes from the choices given. 
     List I                                                 List II
   (Hydride)                                    (Type of hydride)
A. $BeH _{2}$                        1.  Complex
B.. $AsH _{3}$                       2. Lewis acid
C. $B _{2}H _{6}$                   3. Interstitial
D. $LaH _{3}$                        4. Covalent
E. $LiAlH _{4}$                      5. Intermediate

hydrides hydrogen and its compounds hydrogen chemistry

  1. A-6, B-2, C-4, D-5, E-1

  2. A-6, B-2, C-4, D-3, E-1

  3. A-6, B-4, C-2, D-3, E-15

  4. A-5, B-4, C-2, D-3, E-1

Show answer
Correct Option: D
Explanation:

$A.$ $BeH _2\rightarrow$ Intermediate

$B.$ $AsH _3\rightarrow$ Covalent
$C.$ $B _2H _6\rightarrow$ Lewis acid
$D.$ $LaH _3\rightarrow$ Interstitial
$E.$ $LiAlH _4\rightarrow$ Complex

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

column I column II
A NaH i Interstitial hydride 
B $CH _{4}$ ii Molecular hydride
C $VH _{0.56}$ iii Ionic hydride 
D $B _{2}H _{6}$ iv  Electron-deficient hydride 
hydrides hydrogen and its compounds hydrogen chemistry

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

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

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

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

Show answer
Correct Option: D
Explanation:
NaH is an ionic compound and is made of sodium cations $\left ( Na^{+} \right )$ and hydride anions $\left ( H^{-} \right )$. It has the octahedral crystal structure with each sodium ion surrounded by six hydride ions.

$CH _{4}$ forms molecular or covalent hydrides. These are mainly formed by p - block elements and some s - block elements.

The third compound has an oxidation number of hydrogen which is zero. So it belongs to Interstitial hydride.

In $B _{2}H _{6}$ the Boron atom is surrounded by 6 electrons, so it is electron deficient due to its incomplete octet.

The correct option is D.

Correct order of ionic character is:

hydrides hydrogen and its compounds hydrogen chemistry

  1. $CaH _2 < BaH _2 < CH _4$

  2. $CH _4 < CaH _2 < BaH _2$

  3. $CH _4 < BaH _2 < CaH _2$

  4. $BaH _2< CaH _2 < CH _4$

Show answer
Correct Option: C