1
MCQ (Single Correct Answer)
Consider the isoelectronic species, $\mathrm{Na}^{+}, \mathrm{Mg}^{2+}, \mathrm{F}^{-}$and $0^{2-}$. The correct order of increasing length of their radii is
A
$\mathrm{F}^{-}<\mathrm{O}^{2-}<\mathrm{Mg}^{2+}<\mathrm{Na}^{+}$
B
$\mathrm{Mg}^{2+}<\mathrm{Na}^{+}<\mathrm{F}^{-}<\mathrm{O}^{2-}$
C
$\mathrm{O}^{2-}<\mathrm{F}^{-}<\mathrm{Na}^{+}<\mathrm{Mg}^{2+}$
D
$\mathrm{O}^{2-}<\mathrm{F}^{-}<\mathrm{Mg}^{2+}<\mathrm{Na}^{+}$
2
MCQ (Single Correct Answer)
Which of the following is not an actinoid?
A
Curium ( $Z=96$ )
B
Californium $(Z=98)$
C
Uranium $(Z=92)$
D
Terbium $(Z=65)$
3
MCQ (Single Correct Answer)
The order of screening effect of electrons of $s, p, d$ and $f$ orbitals of a given shell of an atom on its outer shell electrons is
A
$s>p>d>f$
B
$f>d>p>s$
C
$p< d< s >f$
D
$f>p>s>d$
4
MCQ (Single Correct Answer)
The first ionisation enthalpies of $\mathrm{Na}, \mathrm{Mg}, \mathrm{Al}$ and Si are in the order
A
$\mathrm{Na}<\mathrm{Mg}>\mathrm{Al}<\mathrm{Si}$
B
$\mathrm{Na}>\mathrm{Mg}>\mathrm{Al}>\mathrm{Si}$
C
$\mathrm{Na}<\mathrm{Mg}<\mathrm{Al}<\mathrm{Si}$
D
$\mathrm{Na}>\mathrm{Mg}>\mathrm{Al}<\mathrm{Si}$
5
MCQ (Single Correct Answer)
The electronic configuration of gadolinium (Atomic number 64) is
A
$[\mathrm{Xe}] 4 f^3 5 d^5 6 s^2$
B
$[\mathrm{Xe}] 4 f^7 5 d^2 6 s^1$
C
$[\mathrm{Xe}] 4 f^7 5 d^1 6 s^2$
D
$[\mathrm{Xe}] 4 f^8 5 d^6 6 s^2$