<u>Answer:</u> The mass of methanol that must be burned is 24.34 grams
<u>Explanation:</u>
We are given:
Amount of heat produced = 581 kJ
For the given chemical equation:

By Stoichiometry of the reaction:
When 764 kJ of heat is produced, the amount of methanol reacted is 1 mole
So, when 581 kJ of heat will be produced, the amount of methanol reacted will be = 
To calculate mass for given number of moles, we use the equation:

Moles of methanol = 0.7605 moles
Molar mass of methanol = 32 g/mol
Putting values in above equation, we get:

Hence, the mass of methanol that must be burned is 24.34 grams
Answer: Oil: covalent
Cornstarch: Covalent
Sodium chloride: Ionic
Sodium bicarbonate: Ionic
Explanation: Covalent compounds are formed by sharing of electrons between non metals whereas ionic compounds are formed by transfer of electrons from metals to non metals.
1. Oil, which is built from the nonmetals hydrogen, carbon, and oxygen: forms a covalent compound by sharing of electrons between non metals hydrogen, carbon, and oxygen. Covalent compounds are insoluble in water.
2. Cornstarch, a carbohydrate consisting of hydrogen, carbon, and oxygen: forms a covalent compound by sharing of electrons between non metals hydrogen, carbon, and oxygen. Covalent compounds are insoluble in water.
3. Sodium chloride (table salt), whose formula is NaCl is formed by transfer of electrons from sodium to chlorine.Ionic compounds are soluble in water.
4. Sodium bicarbonate, whose formula is
is formed by transfer of electrons from sodium to
.Ionic compounds are soluble in water.