Please help me guys and follow my account
CH - Air and Atmosphere
Class - 7th
F. Give reasons for the following.
1. Manganese dioxide is mixedwith potassium chlorate to release oxygen. 2. Rusting is a slow oxidation.
3. Magnesium gains mass, whereas, wood loses mass on burning in air.
4. Rhizobium is a friendly bacterium.
5. Nitrogen is used to preserve food items such as potato chips.
6. Air is a mixture.
Answers
Answer:
1. When potassium chlorate (KClO3) is heated in the presence of manganese dioxide catalyst, it decomposes to form potassium chloride and oxygen gas.
The balanced chemical equation is
2KClO 3→Δ 2KCl+3O 2
2. The oxygen atoms bond with iron atoms, resulting in the formation of iron oxides. This weakens thye bonds between the iron atoms in the object/structure. The reaction of the rusting of iron involves an increase in the oxidation state of iron, accompanied by a loss of electrons.
3. The increase in mass is due to the fact that oxygen from the air has combined with the magnesium to make magnesium oxide, MgO.
4.Rhizobium–legume symbioses are of great ecological and agronomic importance, due to their ability to fix large amounts of atmospheric nitrogen. These symbioses result in the formation on legume roots of differentiated organs called nodules, in which the bacteria reduce nitrogen into ammonia used by the host plant.
5.Chips packets are filled with nitrogen because it is an inert gas, which prevents the oxidation of oils present in chips. So, chips remain fresh.
6.Air is considered as a mixture because of the following reasons: > It is possible to separate air into its constituent gases by means of physical methods like fractional distillation. ... So, when liquefied air is distilled, nitrogen is separated out first and oxygen is left in the mixture.