While filling up of electrons in the atomic orbitals, the 4 s orbital is filled before the 3d orbital but reverse happens during the ionisation of the atom. Explain why?
During filling up of electrons follow $(n+l)$ rule. Here $4 s$ has lower energy than $3 d$ orbital. After the orbitals are filled 4 s goes beyond $3 d$, i.e., $4 s$ is farther from nucleus than $3 d$. So, electron from $4 s$ is removed earlier than from $3 d$.
Reactivity of transition elements decreases almost regularly from Se to Cu . Explain.
Reactivity of transition elements depends mostly upon their ionisation enthalpies. As we move from left to right in the periodic table ( Se to Cu ), ionisation enthalpies increase almost regularly. Hence, their reactivity decreases almost regularly from Se to Cu .
Match the catalysts given in Column I with the process given in Column II.
| Column I (Catalyst) |
Column II (Process) |
||
|---|---|---|---|
| A. | Ni in the presence of hydrogen | 1. | Ziegler-Natta catalyst |
| B. | $\mathrm{Cu_2Cl_2}$ |
2. | Contact process |
| C. | $\mathrm{V_2O5}$ | 3. | Vegetable oil to ghee |
| D. | Finely divided iron | 4. | Sandmeyer reaction |
| E. | $\mathrm{TiCl_4+Al(CH_3)_3}$ | 5. | Haber's process |
| 6. | Decomposition of $\mathrm{KClO_3}$ |
A. $\rightarrow(3)$ B. $\rightarrow$ (4) C. $\rightarrow$ (2) D. $\rightarrow(5)$ E. $\rightarrow(1)$
| (Catalyst) | (Process) | ||
|---|---|---|---|
| A. | Ni in the presence of hydrogen | 1. | Vegetable oil to ghee |
| B. | $\mathrm{Cu_2Cl_2}$ |
2. | Sandmeyer reaction |
| C. | $\mathrm{V_2O5}$ | 3. | Contact process $\mathrm{SO}_2 \xrightarrow{\mathrm{~V}_2 \mathrm{O}_5} \mathrm{SO}_3$ |
| D. | Finely divided iron | 4. | Haber's process $\mathrm{N}_2+3 \mathrm{H}_2 \xrightarrow{\mathrm{Fe}} 2 \mathrm{NH}_3$ |
| E. | $\mathrm{TiCl_4+Al(CH_3)_3}$ | 5. | Ziegler-Natra catalyst |
Match the compounds/elements given in Column I with uses given in Column II.
| Column I (Compound/element) |
Column II (Use) |
||
|---|---|---|---|
| A. | Lanthanoid oxide | 1. | Production of iron alloy |
| B. | Lanthanoid | 2. | Television screen |
| C. | Misch metal | 3. | Petroleum cracking |
| D. | Magnesium based alloy is constituent of | 4. | Lanthanoid metal + iron |
| E. | Mixed oxides of lanthanoids are employed | 5. | Bullets |
| 6. | X-ray screen |
A. $\rightarrow(2)$ B. $\rightarrow$ (1) C. $\rightarrow(4)$ D. $\rightarrow$ (5) E. $\rightarrow(3)$
| (Compound/element) | (Use) | ||
|---|---|---|---|
| A. | Lanthanoid oxide | 1. | Television screen |
| B. | Lanthanoid | 2. | Production of iron alloy |
| C. | Misch metal | 3. | Lanthanoid metal + iron |
| D. | Magnesium based alloy is constituent of | 4. | Bullets |
| E. | Mixed oxides of lanthanoids are employed | 5. | Petroleum cracking |
Match the properties given in Column I with the metals given in Column II.
| Column I (Property) |
Column II (Metal) |
||
|---|---|---|---|
| A. | An element which can show +8 oxidation state | 1. | Mn |
| B. | 3d block element that can show upto +7 oxidation state | 2. | Cr |
| C. | 3d block element with highest melting point | 3. | Os |
| 4. | Fe |
A. $\rightarrow(3)$ B. $\rightarrow$ (1) C. $\rightarrow(2)$
A. Osmium is an element which can show +8 oxidation state.
B. $3 d$ block element that can show upto +7 oxidation state is manganese.
C. $3 d$ block element with highest melting point is chromium.