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.
What current will deposit 3.25g of zinc in 2hrs?
[Zn = 65, F = 96500 mol-]
3.25A
2.00A
1.34A
0.67A
Correct answer is C
No explanation has been provided for this answer.
Which of the following metals is purified commercially by electrolysis?
Zn
Fe
Sn
Cu
Correct answer is D
Electrolysis is used extensively in metallurgical processes, such as in extraction (electrowinning) or purification (electrorefining) of metals from ores or compounds and in deposition of metals from solution (electroplating).
Copper is purified by electrolysis . Electricity is passed through solutions containing copper compounds, such as copper(II) sulfate.
The oxidation state of Cr in K\(_2\)Cr\(_2\)O\(_7\) is?
+7
+6
+5
4
Correct answer is B
Potassium dichromate, K\(_2\)Cr\(_2\)O\(_7\)
→ [1 * 2] + [Cr * 2] + [-2 * 7] = 0
→ 2 + 2Cr - 14 = 0
→ 2Cr = 12
→Cr = \(\frac{12}{2}\) → 6
yellow to purple
orange to green
green to orange
purple to yellow
Correct answer is B
Reducing agent like SO\(_2\).
Sulphur dioxide gas (SO\(_2\)) is bubbled through acidified potassium dichromate. The orange solution turns green.
The salt formed from a reaction between citric acid and sodium hydroxide in solution will be?
acidic
basic
complex
neutral
Correct answer is B
Citric acid has 3 carboxyl groups, therefore, when reacts with NaOH, there is a simple salification reaction that will produce the trisodium citrate / sodium citrate. Trisodium citrate is a tribasic salt of citric acid. It is produced by complete neutralization of citric acid with high purity sodium hydroxide or carbonate and subsequent crystallization and dehydration.