13
MCQ (Single Correct Answer)
Chlorine exists in two isotopic forms. $\mathrm{Cl}-37$ and $\mathrm{Cl}-35$ but its atomic mass is 35.5. This indicates the ratio of $\mathrm{Cl}-37$ and $\mathrm{Cl}-35$ is approximately
A
$1: 2$
B
$1: 1$
C
$1: 3$
D
$3: 1$
14
MCQ (Single Correct Answer)
The pair of ions having same electronic configuration is ............ .
A
$\mathrm{Cr}^{3+}, \mathrm{Fe}^{3+}$
B
$\mathrm{Fe}^{3+}, \mathrm{Mn}^{2+}+$
C
$\mathrm{Fe}^{3+}, \mathrm{Co}^{3+}$
D
$\mathrm{Sc}^{3+}, \mathrm{Cr}^{3+}$
15
MCQ (Single Correct Answer)
For the electrons of oxygen atom, which of the following statements is correct?
A
$Z_{\text {eff }}$ for an electron in a $2 s$ orbital is the same as $Z_{\text {eff }}$ for an electron in a $2 p$ orbital
B
An electron in the $2 s$ orbital has the same energy as an electron in the $2 p$ orbital
C
$Z_{\text {eff }}$ for an electron in $1 s$ orbital is the same as $Z_{\text {eff }}$ for an electron in a $2 s$ orbital
D
The two electrons present in the $2 s$ orbital have spin quantum numbers $m_s$ but of opposite sign
16
MCQ (Single Correct Answer)
If travelling at same speeds, which of the following matter waves have the shortest wavelength?
A
Electron
B
Alpha particle $\left(\mathrm{He}^{2+}\right)$
C
Neutron
D
Proton
17
MCQ (Multiple Correct Answer)
Identify the pairs which are not of isotopes?
A
${ }_6^{12} X,{ }_6^{13} Y$
B
${ }_{17}^{35} X,{ }_{17}^{37} Y$
C
${ }_6^{14} X,{ }_7^{14} Y$
D
${ }_4^8 X,{ }_5^8 Y$