Answer : The balanced chemical equation will be:
(i) 
(ii) 
Explanation :
Balanced chemical equation : It is defined as the equation in which total number of individual atoms on the reactant side is equal to the total number of individual atoms on product side.
Part (i):
The balanced chemical equation will be:

This reaction is a single displacement reaction in which most reactive element (potassium) displaces the least reactive element (hydrogen) form their solution.
Part (ii):
The balanced chemical equation will be:

This reaction is a single displacement reaction in which most reactive element (zinc) displaces the least reactive element (magnesium) form their solution.
Explanation:
The electronegativity difference in C-C and C-H atoms is quite low. This means smaller the electron cloud. This further means larger bond length that is electron's are further from the nucleus. hence, higher potential energy of C-C and C-H bonds.
On the contrary, C-O and H-O have large difference in electronegativity( O is high electronegative element) . This means smaller bond length. Electron's near the nucleus. Thus, lower potential energy of bonds.
This follows the law of conservation of momentum. Momentum is the product of mass and velocity of object.
Momentum = mass(m) x velocity(v)
law of conservation of momentum means that the total momentum of system before the collision of 2 objects is equal to the total momentum after the collision
Before the collision total momentum
= m1v1 + m2v2
m1 = 2 kg
v1 = 2 m/s
m2 = 6 kg
v2 = 0 m/s
substituting the values in the equation
total momentum before = (2 kg x 2 m/s) + (6 kg x 0 m/s)
total momentum = 4 kgm/s
after the collision the 2 objects stick together and have a common velocity
total momentum after the collision = (6 kg + 2 kg)x V = 8V
V = speed of the conglomerate particle
since total momentum before is equal to total momentum after
8V = 4
V = 2 m/s
speed of conglomerate particle is 2 m/s
A.fluoride
Fluoride helps to prevent tooth decay
<h3><u>Answer; </u></h3>
=10.38 moles KOH
<h3><u>Explanation</u>;</h3>
The balanced equation.
6KOH + Al2(SO4)3 --> 3K2SO4 + 2Al(OH)3
From the equation;
1 mole of aluminum sulfate requires 6 moles of potassium hydroxide.
Moles of Aluminium sulfate; 1.73 moles
Moles of KOH;
1 mol Al2(SO4)3 : 6 mol KOH = 1.73 mol Al2(SO4)3 : x mol KOH
Thus; x = (6 × 1.73)
<u> =10.38 moles KOH </u>