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 circular path through which electrons revolve round the nucleus
a region around the nucleus where electrons are most likely to be found
the path around the nucleus through which electrons move
the path around the nucleus through which protons move
Correct answer is B
The orbital is a path or region around the nucleus. The electrons move in the orbitals and not through it.
The mass of one mole of (NH4)2CO3 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
= (2×14.0)+(8×1.0)+12.0+(16.0×3)
= 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
Zn2+
Sc3+
Cu
Mn
Correct answer is B
Scandium has electronic configuration 1s22s22p63s23p63d14s2 hence, Sc3+ has configuration 1s22s22p63s23p6. Hence, no electron in the 3d-orbital.