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.
In the redox reaction\( 2Fe^{2+} + CI_2 → 2Fe^{3+} + 2Cl^-\)
Cl2 is reduced because it has lost electrons
Cl2 is reduced because its oxidation number has decreased
Cl2 is reduced because its molecule is change to two ions
Fe2+ is reduced because it has lost electrons
Fe2+ is reduced because it has gained electrons
Correct answer is B
decrease in oxidation number indicates reduction while an increase in oxidation number indicates oxidation hence chloride gas is reduced because its oxidation number changed from o to -1
In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because
it makes bauxite a better conductor of electricity
it makes bauxite melt at a lower temperature
it makes aluminium purer
it prevents aluminium from getting oxidized
it protects the carbon electrodes used in the process
Correct answer is B
The bauxite is purified to yield a white powder, aluminium oxide, from which aluminium can be extracted. The extraction is done by electrolysis. ... Instead, it is dissolved in molten cryolite, an aluminium compound with a lower melting point than aluminium oxide.
Which one of these compounds will NOT give an oxygen gas on heating?
Manganese dioxide
Hydrogen peroxide
Zinc nitrate
Sodium nitrate
Ammonium nitrate
Correct answer is E
No explanation has been provided for this answer.
64.0g
32.0g
16.0g
6.4g
3.2g
Correct answer is E
CuSO4 \(\to\) Cu2+ + SO42+
Cu2+ + 2e \(\to\) Cu
1 Faraday will deposit \(\frac{64}{2}\)gms of copper
0.1 faraday will deposit \(\frac{64}{2} \times \frac{1}{10} = \frac{64}{20}\)
= \(\frac{32}{10}\) = 3.2gms
atomic number of elements increases
atomic mass of elements increases
electropositive character of elements increases
electronegative character of elements increases
number of electrons in the outermost orbits of element increases
Correct answer is C
No explanation has been provided for this answer.