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.
0.89 mol
1.90 mol
3.80 mol
5.70 mol
Correct answer is A
No explanation has been provided for this answer.
negative
zero
positive
indeterminate
Correct answer is A
\(\begin{array}{c|c}
\text{Enthalpy Change [ΔH]} & \text{Entropy Change [ΔS]} & \text{Gibbs free Energy[ΔG]} \\
\hline
\text{Positive} & \text{Positive} & \text{depends on T, may be + or -} \\ \hline \text{Negative} & \text{Positive} & \text{always negative} \\ \hline \text{Negative} & \text{Negative} & \text{depends on T, may be + or -} \\ \hline \text{Positive} & \text{Negative} & \text{always positive} \end{array}\)
ΔG= ΔH − TΔS.
To determine whether ΔG will be positive or negative, the value of ΔH(change in enthalpy) and ΔS (change in entropy) must be given. Likewise the temperature.
Ca(OH)2(s) + 2NH4Cl(s) → CaCl2(s) + 2H2O(l) + X. In the reaction above X is
NO2
NH3
N2O
NO2
Correct answer is B
Balancing the chemical equation.
Ca[OH]2 + 2NH4Cl → CaCl2 + 2H2O + 2NH3
X = NH3
Water for town supply is chlorinate to make it free from
bad colour
bacteria
temporary hardness
permanent hardness
Correct answer is B
Chlorine helps to keep water from germs and bacteria.
The furring of kettles is caused by the presence in water of
calcium hydrogentrioxocarbonate (IV)
calcium trioxocarbonate (IV)
calcium tetraoxosulphate (VI)
calcium hydroxide
Correct answer is B
Furring of kettles is caused by the temporary hardness in water. Temporary hardness in water is caused by calcium and magnesium trioxocarbonate (IV)
CaCO3 causes the furring of kettles