131.

Pick out the isoelectronic structures from the following

$\underset{\mathrm{I}}{{\mathrm{CH}}_3^{+}} \underset{\mathrm{II}}{{\mathrm{H}}_3{\mathrm{O}}^{+}} \underset{\mathrm{III}}{{\mathrm{NH}}_3} \underset{\mathrm{IV}}{{\mathrm{CH}}_3^{-}}$

• I and II

• I and IV

• I and III

• II, III and IV

The first ionisation potential of Na, Mg, Al and Si are in the order

• Na < Mg > Al < Si

• Na > Mg > Al > Si

• Na < Mg < Al > Si

• Na > Mg > Al < Si

Elements of which group form anions most readily?

• Oxygen group

• Nitrogen group

• Halogens

• Alkali metals

Which of the following elements is present in red blood cells of man?

• Fe

• Ra

• Co

• None of these

Which of the following has magnesium?

• Haemoglobin

• Chlorophyll

• Vitamin B₁₂

• Haemocyanin

Indicate the pair whose one member has the highest and other has the lowest electronegativity

• I and F

• Fr and Li

• K and Cs

• F and Fr

Pure nitrogen gas is obtained from

• NH₃ + NaNO₂

• NH₄Cl + NaNO₂

• N₂O + Cu

• (NH₄)₂Cr₂O₇

The Modern Periodic Table is based on the properties of elements as a function of

• atomic number

• atomic mass

• electronegatvity

• electron affinity

Atomic numbers of elements X, Y and Z are 50, 78 and 60 respectively. These elements are placed in modem long form of Periodic Table respectively in

• p-block, d-block and f-block

• p-block, d-block and s-block

• s-block, p-block and d-block

• s-block, d-block and f-block

What is the electronic configuration of O^2- ion?

• 1s², 2s², 2p⁵, 3s¹

• 1s², 2s², 2p⁴, 3s²

• 1s², 2s², 2p⁶

• 1s², 2s², 2p⁴