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.
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
Due to the high reactivity of sodium, it is usually stored under
water
mercury
paraffin
phenol
Correct answer is C
Na is kept under kerosene (paraffin) to avoid reactivity with air.
Paraffin is also known as Kerosene.
Na(sodium) is kept in kerosene to prevent it from coming in contact with oxygen and moisture. If this happens, it will react with the moisture present in air and form sodium hydroxide.
10.0s
12.5s
17.7s
32.0s
Correct answer is B
Rate of diffusion \(\frac{\alpha_1}{Density}\) or \(\frac{1}{\sqrt{Mm}}\)
Rate = \(\frac{1}{time}\)
\(\frac{1}{time}\) \(\frac{\alpha_1}{Density}\) or \(\frac{1}{\sqrt{Molarmass}}\)
Time \(\alpha \sqrt{Density}\) or \(\sqrt{Molarmass}\)
At constant volume of 100cm3
\(\frac{t_{o2}}{\sqrt{Mn_{o2}}}\) = \(\frac{t_{n2}}{\sqrt{1 \times 2}}\)
\(\frac{50}{4 \sqrt{2}}\) = \(\frac{t_{n2}}{\sqrt{2}}\)
tn2= 12.5s