Answer: 
Explanation
Combustion is a chemical reaction in which hydrocarbons are burnt in the presence of oxygen to give carbon dioxide and water.
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The balanced combustion reaction for butane is,:

Answer: 1: B. It will speed up the reaction.
2: A. Increase the concentration of a reactant.
3: A. They act as catalysts.
4: C. A catalyst decreases the activation energy needed for a reaction.
5: D. collision theory.
Explanation: I just took the quiz:)
Answer:
Moon has to be in-between the Earth and the Sun.
2. Moon's umbra should sweep your place.
3. Latitude and longitude of your place should be within the befitting limits.