A. Al3+
B. Fe2+
C. Si4+
D. Ca2+
E. Na+
Choose the correct answer from the options given below :
The question requires ordering specific elements by their average weight percentage in the Earth's crust, from highest to lowest. The ionic charges provided do not affect the elemental abundance percentages.
Key elements and their approximate average composition by weight in the Earth's crust are:
| Element | Symbol (Option) | Approx. % by Weight |
| Silicon | C ($Si^{4+}$) | ~27.7% |
| Aluminum | A ($Al^{3+}$) | ~8.1% |
| Iron | B ($Fe^{2+}$) | ~5.0% |
| Calcium | D ($Ca^{2+}$) | ~3.6% |
| Sodium | E ($Na^{+}$) | ~2.8% |
Arranging these elements in decreasing order based on abundance:
This sequence corresponds to the order C, A, B, D, E.
Morgenthau's principles of political realism are:
A. Politics is rooted in permanent and unchanging human nature which is basically self centred, self-regarding and self-interested
B. Politics is an autonomous sphere of action and cannot therefore be reduced to morals
C. International Politics is an arena of conflicting self-interests
D. The ethics of international relations is situational ethics which is very different from private morality
Choose the correct answer from the options given below:
Who among the following political thinkers consider the anarchical self help system to be a compelling factor for States to maximise their relative power positions?