Answer:
a) Step 1:

Step 2:

b) The overall balanced reaction for given process is ;

Explanation:
a)
Galena = 
Lead(II) oxide = 
Sulfur dioxide = 
Step 1:
Roasting the galena in oxygen gas to form lead(II) oxide and sulfur dioxide.
Balanced equation of step 1:
..[1]
Step 2:
Heating the metal oxide with more galena forms the molten metal and more sulfur dioxide.
Balanced equation of step 2:
..[2]
b)
For over all reaction add [1] and [2]. The overall balanced reaction for given process is ;

Answer:
A substance which burns in air and tends to produce heat and light is known as Combustible substances. Non-combustible substances are certain substances which are not combustible in the presence of air. Will not burn on being exposed to flame.
Answer:
5
Explanation:
chemical formulas show what atoms are in a molecule. In this case there is 1 hydrogen (H), 1 chlorine (Cl), and 3 oxygens (O). The 3 behind the oxygen is a subscript and tells us that there are 3 oxygen atoms.
Another example is H2O which as 3 atoms. 2 hydrogens (H) and 1 oxygen (O). This formula has a subscript 2 behind the hydrogen showing that there are 2 hydrogens.
Answer:
[Kr] 4d10 5s2 5p4
Explanation:
The Symbol I represents Iodine. It has atomic number of 53. The full electronic configuration is given as;
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p5
However the question requested for the configuration of I+.
I+ is a cation and it simply refers to an iodine atom that has lost a single electron. The electronic configuration of I+ is given as;
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p4
Using Noble gas shorthand representation, we have;
[Kr] 4d10 5s2 5p4