magnesium oxide is: MgO (right side)
so the left side is: Mg + O2
for the equation to be balanced there must be two oxygens on both sides
Mg + O2 = 2MgO
but now the magnesium is uneven, so there must be two magnesiums on each side
the answer is: B) 2Mg + O2 = 2MgO
Hexane and 2-methylpentane. If you draw the structures out, you can see that both isomers have 6 carbon atoms and 14 hydrogen atoms. Hence they have the same molecular formula but a different structural formula. I suggest drawing the compounds out for these types of questions to visualise it.
The mass of ore required is
21 700 t.
r = 750 cm
V =

=

= 1.767 × 10⁹ cm³
The density of lead is 11.34 g/cm³.
So mass of lead sphere = 1.767 × 10⁹ cm³ ×

= 2.004 ×10¹⁰ g
2.004 ×10¹⁰ g ×

= 2.004 × 10⁷ kg
2.004 × 10⁷ kg ×

= 2.004 × 10⁴ t
92.5% efficiency means 92.5 t Pb per 100 t of ore.
Mass of ore = 2.004 × 10⁴ t Pb ×

= 2.17 × 10⁴ t ore = 21 700 t ore
Answer:
1 and 3
Explanation:
The vertical columns (groups) of the periodic table are arranged such that all its elements have the same number of valence electrons. All elements within a certain group thus share similar properties.