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.
Which of the following reaction is endothermic?
C(s) + O2(g) → CO2(g)
CaO(s) + H2O(l) → Ca(OH)2(s)
C(s) + H2O(g) → CO(g) + H2(g)
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
Correct answer is C
Water Gas is a mixture of carbon monoxide and hydrogen produced from synthesis gas.\(H_2O + C --> H_2 + CO\) (H=+131KJ/mol)
An Endothermic process is any process which requires or absorbs thermal energy from its surroundings, usually in the form of heat.in Endothermic reaction ∆H is positive.
Therefore it is Endothermic
\(NH_{3(g)} + HCl_{(g)} → NH_4Cl_{(s)}\)
The entropy change in the system above is
positive
zero
negative
indeterminate
Correct answer is C
\(NH_{3(g)} + HCl_{(g)} → NH_4Cl_{(s)}\)
Reactant = 2 moles of gaseous molecules
Product = 1 mole of gaseous molecule
Entropy change = 1 - 2 = -1 (negative)
1.00g
2.01g
4.02g
8.04g
Correct answer is B
At the cathode, we have:
\(Zn^{2+} + 2e^- → Zn_{(s)}\)
Normally, we need
2F → 65g
x → 0.65
x = 0.02F
Let us check how much mercury will be deposited by 0.02F of electricity
\(Hg^{2+} + 2e^-(aq) → Hg_{(s)}\)
2F → 201g
∴ 0.02F = x
x = 2.01g
In recharging a lead-acid accumulator, the reaction at the cathode can be represented as
Pb2+(aq) + SO2-4(aq) →PbSO4(s)
Pb2+(aq) + 2e- →Pb(s)
Pb2+(aq) + 2H2O(l) → PbO2(s) + 4H+(aq) + 4e-
Pb(s) → Pb2+(aq) + 2e-
Correct answer is B
In lead acid ,lead dissociates at the cathode Pb2+(aq) + 2e- →Pb(s)
What is the IUPAC nomenclature of the compound NaCIO?
sodium oxochlorate (I)
sodium chloro (I) oxide
sodium monooxochlorate (II)
sodium chloro (I) monoxide
Correct answer is A
NaClO is sodium oxochlorate(I) in IUPAC nomenclature