The law of conservation of mass applies to both cases, the following will explain how:
1. When 50 g of sugar undergoes a physical change, say for example dissolving or melting, the amount of sugar in the solution or melted form will also be 50 grams. This shows that the mass before and after the change was the same, in accordance to the law of conservation of mass.
2. When the magnesium strip is burned, this is a chemical reaction. The problem is that we only measure the mass of one of the substances involved in the reaction, the magnesium strip, which makes it seem like the mass has increased. Actually, during burning, the magnesium combines with oxygen in the air. This oxygen was present before the reaction, we just did not measure it. And after the reaction it is present in the form of product. Therefore, mass is still conserved.
Answer:
See the answer below
Explanation:
1. Organisms produce energy for cells by chemically breaking down and unlocking the energy locked-up within food materials in a process known as cellular respiration. The unlocked energy is then utilized for the cell's metabolic activities.
2. Cellular respiration can be aerobic or anaerobic.
Aerobic respiration involves the breakdown of carbohydrates in the presence of oxygen to yield energy in the form of ATP while carbon dioxide and water are produced as by-products.

Anaerobic respiration involves the breakdown of carbohydrates in the absence of oxygen to produce ATP and lactic acid as a by-product. The lactic acid is later oxidized to carbon dioxide and water to prevent it from building up.

3. Photosynthesis and cellular respiration are both considered metabolic processes that take place in living organisms. However, photosynthesis is peculiar only to green plants and some algae while respiration is common to all living organisms. While photosynthesis is anabolic, that is, it involves the building up of materials; respiration is said to be catabolic because it involves the breaking down of materials.
During photosynthesis, inorganic products are utilized to produce carbohydrates for plants with oxygen gas released as a by-product according to the following equation:

During respiration, the food taken by living organisms is broken down to unlock the energy in it for metabolic activities according to the following equation:

Answer:
Gases are easily compressed because of the space between the particles in a gas. ... The pressure decreases because the kinetic energy decreases with the temperature and slower moving particles impact the walls of a contain with less energy.
250cm3 i think im not sure about it though