Core, radiative zone, convection zone, photosphere, chromosphere, corona.
Answer:
2Mg(s) +O₂(g) → 2MgO(s)
Explanation:
Mg(s) +O₂(g) → MgO(s)
When a chemical equation is balanced, the number of atoms of each element is equal on both sides of the arrow. We usually balance O and H last.
In this case, the number of Mg atoms is equal on both sides. Thus, let's move on to balance the O atoms. On the left side, there are 2 O atoms, while there is only 1 O atom on the left side. Thus, write a '2' in front of MgO.
Mg(s) +O₂(g) → 2MgO(s)
Now, the number of Mg atoms is not equal. Write a '2' in front of Mg to balance it.
2Mg(s) +O₂(g) → 2MgO(s)
The equation is now balanced with 2 Mg atoms and 2 O atoms on each side.
Answer: 1. C. polar covalent: electrons shared between silicon and sulfur but attracted more to the sulfur
2. B) 
3. B) Fluorine
Explanation:
1. A polar covalent bond is defined as the bond which is formed when there is a difference of electronegativities between the atoms.
Electronegativity difference = electronegativity of sulphur- electronegativity of silicon = 2.5 -1.8 = 0.7
Thus as electronegativity difference is less than 1.7 , the cond is polar covalent and as electronegativity of sulphur is more , the electrons will be more towards sulphur.
2. A molecular compound is usually composed of two or more nonmetal elements. Example:
Ionic compound is formed by the transfer of electrons from metals to non metals. Example:
,
and 
3. For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here K is having an oxidation state of +1 and as the compound formed is KZ, the oxidation state of non metallic element Z should be -1. Thus the element Z is flourine which exists as diatomic gas 
150 g SO₂ = 2.36 mol SO₂
M_r = 32.06 + 2×16.00 = 32.07 + 32.00 = 64.06
Moles of SO₂ = 151 g SO₂ × [1 mol SO₂/64.06 g SO₂] = 2.36 mol SO₂