A for the first and b for the second!!:))
2Mg+O₂⇒2MgO
It can be a combustion reaction, or it can be a combination reaction
I think C-I
It can also be wrong but that’s my opinion
Sound actually travels slower in air.This is because sound is kinetic energy and has to pass from molecule to molecule.In gas the molecules are farther apart taking more time for it to pass,in water the molecules are closer so it takes less time for the sound to get from one molecule to another and with cast iron (since it's very dense) the molecules are very close allowing sound to travel quickly with ease.
Answer:
6,216.684 kilograms of sodium carbonate must be added to neutralize
of sulfuric acid solution.
Explanation:
Mass of sulfuric acid solution = 

Percentage mass of sulfuric acid = 95.0%
Mass of sulfuric acid = 

Moles of sulfuric acid = 

According to reaction , 1 mole of sulfuric acid is neutralized by 1 mole of sodium carbonate.
Then 58,647.96 moles of sulfuric acisd will be neutralized by :
of sodium carbonate
Mass of 58,647.96 moles of sodium carbonate :

6,216,683.76 g = 6,216,683.76 × 0.001 kg = 6,216.684 kg
6,216.684 kilograms of sodium carbonate must be added to neutralize
of sulfuric acid solution.