2019 - JAMB Chemistry Past Questions and Answers - page 5
Which of the following is a physical change?
In the reaction between sodium hydroxide and tetraoxosulphate (VI) solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralize 10cm\(^3\) of 1.25 molar tetraoxosulphate (vi) acid?
25cm\(^3\)
10cm\(^3\)
20cm\(^3\)
50cm\(^3\)
Equation of the reaction is give as: 2NaOH + H\(_2\)SO\(_4\) → Na\(_2\)SO\(_4\) + 2H\(_2\)O
Concentration of a base, CB = 0.5M
Volume of acid, V\(_A\) = 10cm\(^3\)
Concentration of an acid, C\(_A\) = 1.25M
The volume of the base, V\(_B\) = ?
Recall that,
\(\frac{C_A V_A}{C_B V_B} = \frac{n_A}{n_B}\) ... (1)
From the equation is as follows:
\(\frac{n_A}{n_B} = \frac{1}{2}\)
From equation (1),
\(\frac{1.25 \times 10}{0.5 \times V_B} = \frac{1}{2}\)
\(\frac{12.5}{0.5V_B} = \frac{1}{2}\)
25 = 0.5V\(_B\)
VB = 50.0 cm\(^3\)
Sulphur exists in six forms in the solid state. This property is known as
In the reaction:
M + N → P
ΔH = +Q kJ
Which of the following would increase the concentration of the product?
A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180. Find the molecular formula.
[H = 1, C = 12, O = 16]
The IUPAC nomenclature of the compound
H\(_3\)C - CH(CH\(_3\)) - CH(CH\(_3\)) - CH\(_2\) - CH\(_3\)
Which of the following gases contains the least number of atoms at s.t.p?
1 mole of butane
4 moles of chlorine
3 moles of ozone
7 moles of argon
Butane has the least number of atoms, thus:
4 moles of chlorine gas = 4Cl\(_2\) = 8 atoms of chlorine
3 moles of ozone = 3O\(_3\) = 9 atoms of oxygen
1 mole of butane = C\(_4\)H\(_{10}\)
7 mole of argon = 7Ar = 7 atoms of argon
What mass of magnesium would be obtained by passing a current of 2 amperes for 2 hours 30 mins, through molten magnesium chloride?
[1 faraday = 96500C, Mg = 24]
Given:
Current (I) = 2A; Time (t) = 2 hours = 7200 secs
Q = It
= 2 x 7200 = 14400C
1 F = 96500C
x = 14400C
x = \(\frac{14400}{96500}\)
= 0.15F
Mg\(^{2+}\) + 2e\(^-\) \(\to\) Mg
2F \(\to\) 24g
0.15F \(\to\) x
2x = 24 x 0.15
x = \(\frac{24 \times 0.15}{2}\)
= 1.8g
Which important nitrogen-containing compound is produced in Haber's process?
Elements in the periodic table are arranged in the order of their