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

4d, 5p, 5f and 6p orbitals are arranged in the order of decreasing energy. The correct option is: