Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.
The mass of one mole of \((NH_{4})_{2}CO_{3}\) is [O=16.0, N=14.0, C=12.0, H=1.0]
66.0g
76.0g
80.0g
96.0g
Correct answer is D
This is same as asking for the molar mass of the compound
= \((2\times 14.0)+ (8\times 1.0) + 12.0+(16.0\times 3)\)
= 28.0+8.0+12.0+48.0 = 96.0g
The purity of a solid sample can best be determined by its
boiling point
melting point
conductivity
solubility
Correct answer is B
The purity of a solid can be determined by measuring the melting point. A pure solid will have a single, sharp melting point.
The seperation of Nitrogen from oxygen using fractional distillation of air is possible because
nitrogen is less dense than oxygen
oxygen is more reactive than nitrogen
of the difference in their boiling points
they belong to the same period
Correct answer is C
The various gases vaporize as their boiling points are reached, then they are pumped away and separately re-liquefied for convenient storage.
The species with no electron in the 3d-orbital is
\(Zn^{2+}\)
\(Sc^{3+}\)
Cu
\(Mn\)
Correct answer is B
Scandium has electronic configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{1}4s^{2}\) hence, \(Sc^{3+}\) has configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\). Hence, no electron in the 3d-orbital.
Pauli exclusion principle is related to
quantity of electrons in the valence shell
filling the orbitals with lower energy first
the filling of degenerated orbitals
quantum numbers of electrons
Correct answer is D
Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers.