So to balance an equation, you need to get the same amount of each type of element on either side of the --> . So you pretty much are given the subscripts in the equations and you need to add coefficients (just normal numbers) in front of any formula that needs it, keeping anything balance.

turns into

These coefficient numbers are the molar ratios, so 2 moles of KCl3 for every 3 moles of O2 so 1. 3:2
Then you can use these ratios of find out how many moles of one thing are needed if you are given the amount of another.

and use cross multiplication to solve for whatever you don't know
<span />
Answer:
The following reaction will occur at cathode:

Explanation:
The two half reaction during electrolysis of aqueous nickel sulfate will be
a) anode reaction :
Water will undergo oxidation and will evolve oxygen gas at anode as shown in the given reaction:

b) Cathode reaction: The reduction of Nickel ion will occur by gain of two electrons as shown in the given equation:

Thus the overall reaction will be:

Answer:
E = 0.062 V
Explanation:
(a) See the attached file for the answer
(b)
Calculating the voltage (E) using the formula;
E = - (2.303RT/nf)log Cathode/Anode
Where,
R = 8.314 J/K/mol
T = 35°C = 308 K
F- Faraday's constant = 96500 C/mol,
n = number of moles of electron = 2
Substituting, we have
E = -(2.303 * 8.314 *308/2*96500) *log (0.03/3)
= -0.031 * -2
= 0.062V
Therefore, the voltmeter will show a voltage of 0.062 V
The answer is A. It is an alkyn. There is a triple bond