The reason for greater range of oxidation states in actinoid is attributed to the $$5f, 6d$$ and $$7s$$ levels having comparable energies.
The $$5f$$-orbitals extend into space beyond the $$7s$$ and $$6 p$$ -orbitals and participate in bonding. This is in direct contrast to the lanthanides where the $$4f$$-orbitals are buried deep inside the atom, totally shielded by outer orbitals and thus unable to take part in bonding.
83.
A compound of iron exists as a dimer in vapour state. It is hygroscopic in nature and dissolves in water giving brown acidic solution. The compound is
The solution is acidic due to formation of $$HCl$$ and brown due to $$Fe{\left( {OH} \right)_3}.$$
$$FeC{l_3} + 3{H_2}O \to Fe{\left( {OH} \right)_3} + 3HCl$$
84.
Mercury is a liquid metal because
A
it has a completely filled $$d$$ - orbital that prevents $$d{\text{ - }}d$$ overlapping of orbitals
B
it has a completely filled $$d$$ - orbital that causes $$d{\text{ - }}d$$ overlapping
C
it has completely filled $$s$$ - orbital
D
it has small atomic size
Answer :
it has a completely filled $$d$$ - orbital that prevents $$d{\text{ - }}d$$ overlapping of orbitals
The more extensive the metallic bonding of an element, the more will be its enthalpy of atomization. Due to the absence of unpaired electrons in zinc, metallic bonding is weakest and as a result, it has least enthalpy of atomization.
85.
Which of the following is an organometallic compound?
No explanation is given for this question. Let's discuss the answer together.
87.
The electronic configuration of $$Cu\left( {{\text{II}}} \right)$$ is $$3{d^9}$$ whereas that of $$Cu\left( {\text{I}} \right)$$ is $$3{d^{10}}.$$ Which of the following is correct?
A
$$Cu\left( {{\text{II}}} \right)$$ is more stable.
B
$$Cu\left( {{\text{II}}} \right)$$ is less stable.
C
$$Cu\left( {\text{I}} \right)$$ and $$Cu\left( {{\text{II}}} \right)$$ are equally stable.
D
Stability of $$Cu\left( {\text{I}} \right)$$ and $$Cu\left( {{\text{II}}} \right)$$ depends on nature of copper salts.
Answer :
$$Cu\left( {{\text{II}}} \right)$$ is more stable.
Standard electrode potential of $$C{u^ + }$$ is high $$\left( {0.52\,V} \right)$$ as compared to $$C{u^{2 + }}\left( {0.34\,V} \right),$$ hence $$C{u^ + }$$ is reduced more easily and is less stable than $$C{u^{2 + }}.$$
$${\left[ {Cu{I_4}} \right]^{2 - }}$$ does not exist because $${I^ - }$$ being a stronger reducing agent reduces $$C{u^{2 + }}$$ to $$C{u^ + }.$$
$$2Cu{I_2} \to 2CuI + {I_2}$$
89.
In which of the following lanthanoids oxidation state $$+2$$ is most stable ?
$$E{u^{2 + }}$$ has electronic configuration $$\left[ {Xe} \right]4{f^7}$$ hence stable due to half filled atomic orbitals.
90.
In the preparation of $$KMn{O_4}$$ pyrolusite $$\left( {Mn{O_2}} \right)$$ is first converted to potassium manganate $$\left( {{K_2}Mn{O_4}} \right).$$ In this conversion, the oxidation state of manganese changes from