C. A new substance is produced. All others are physical changes.
Answer is: polystyrene.
Expanded polystyrene is used to manufacture foam cups.
Polystyrene production is several million tonnes per year.
Polystyrene is a synthetic aromatic hydrocarbon polymer made from the monomer styrene.
Styrene (ethenylbenzene) is an organic compound with the chemical formula C₆H₅CH=CH₂. It is a colorless oily liquid.
Answer:
The correct answer is option D.
Explanation:
Step 1: 
Step 2: 
Overall reaction can be determined by adding all the reactions of mechanism:
Reactants in an overall reaction = 
Products in an overall reaction = 
According to question , the role of oxygen gas is product.
Answer:
3,4
Explanation:
Hydrogen has no other electron hence there is no screening of the valence electron by inner electrons. It is the lightest known element with a relative molecular mass of 2. Screening effect refers to the fact that inner or core electrons prevent the outermost electron from feeling the attractive force of the nucleus.
Answer:
So the answer is every day
Explanation:
Plants respire at all times of the day and night because their cells need a constant energy source to stay alive.
