The number of d -electrons in Fe²⁺ (atomic number  Z = 26)  is different from the number of:
1. s-electrons in Mg (Z = 12)
2. p-electrons in Cl (Z = 17)
3. d-electrons in Fe (Z = 26)
4. p-electrons in Ne (Z = 10)

The angular momentum of electrons in d orbital is equal to:
1. $\sqrt{6}$ $\sout{h}$
2. $\sqrt{2}$$\sout{h}$
3. $2\sqrt{3}$ $\sout{h}$
4. 0 $\sout{h}$

What is the maximum number of orbitals that can be identified with the following quantum numbers?
n = 3, l = 1, m = 0

Maximum number of electrons in a subshell with l = 3 and n = 4 is:

1. 14

2. 16

3. 10

4. 12

The energies E₁ and E₂ of two radiations are 25 eV and 50 eV respectively. The relation between their wavelengths i.e., ${\mathrm{\lambda }}_1$ and ${\mathrm{\lambda }}_2$ will be:

1.  ${\mathrm{\lambda }}_1=2{\mathrm{\lambda }}_2$

2.  ${\mathrm{\lambda }}_1=4{\mathrm{\lambda }}_2$

3.  ${\mathrm{\lambda }}_1=\frac{1}{2}{\mathrm{\lambda }}_2$

4.  ${\mathrm{\lambda }}_1={\mathrm{\lambda }}_2$

If n = 6, the correct sequence for the filling of electrons will be: 

1. $\mathrm{ns}$ $\stackrel{}{\to }$ $\left(\mathrm{n}-1\right)$ $\mathrm{d}$ $\stackrel{}{\to }$ $\left(\mathrm{n}-2\right)$ $\mathrm{f}$ $\stackrel{}{\to }$ $\mathrm{np}$

2. $\mathrm{ns}$ $-$ $\left(\mathrm{n}-2\right)$ $\mathrm{f}$ $\stackrel{}{\to }$ $\mathrm{np}$ $\stackrel{}{\to }$ $\left(\mathrm{n}-1\right)$ $\mathrm{d}$

3. $\mathrm{ns}$ $-$ $\mathrm{np}$ $\stackrel{}{\to }$ $\left(\mathrm{n}-1\right)\mathrm{d}$ $\stackrel{}{\to }$ $\left(\mathrm{n}-2\right)$ $\mathrm{f}$

4. $\mathrm{ns}$ $\stackrel{}{\to }$ $\left(\mathrm{n}-2\right)$ $\mathrm{f}$ $\stackrel{}{\to }$ $\left(\mathrm{n}-1\right)$ $\mathrm{d}$ $\stackrel{}{\to }$ $\mathrm{np}$

An element X has the following isotopic composition: 
²⁰⁰X: 90% 
¹⁹⁹X: 8.0% 
²⁰²X: 2.0% 
The weighted average atomic mass of the naturally-occurring element X is closest to:

1. 200 amu
2. 201 amu
3. 202 amu
4. 199 amu

Which of the following is the correct arrangement of 4d, 5p, 5f, and 6p orbitals in the order of decreasing energy?