A. Which non-metal is essential for our life and all living beings inhale it during breathing? B. Whichnon-metal is used to disinfect water?

2.A purple coloured non-metal forms a brown solution in alcohol which is applied on wounds as an antiseptic. Name the non-metal.

Give reasons for the following.

(a)Aluminium foils are used to wrap food items.

(b)Immersion rods for heating liquids are made up of metallic substances.

(c)Sodium and potassium are stored in kerosene.

4. What is the nature (acidic or basic )of the following oxides ?a. Magnesium oxide (b) Sulphur dioxideGive reason foryour choice.

5. When a copper metal is exposed to moist air for a long time, then a green coating is formed on its surface .What is the green material formed on its surface. Support your answer with word equation. Is it acidic or basic in nature.

PLEASE HELP ME

A. oxygen

B. chlorine

2. iodine

(a) because aluminium is a soft malleable metal. it can be made to in sheets to form thin wrapping sheets. also, it does not react with food items.

(b) because metals are good conductors of heat and electricity. the immersion rod needs electric supply to get heated and to heat liquids.

(c)  they're kept in kerosene to keep them from coming in contact with oxygen and moisture as they react to form their hydroxides.

4. Magnesium is a metal. Metals react with oxygen to form metallic oxides. So Magnesium oxides are basic in nature. But nonmetals react with oxygen to form nonmetallic oxides. These oxides differ from metallic oxides because they are acidic in nature. Nonmetallic oxides react with water to form acids. Therefore, Sulphur dioxide is acidic in nature. Magnesium oxide is basic in nature.

5. Copper forms a green deposit on its surface when exposed to air which is usually a mixture of copper carbonate and copper hydroxide. It's acidic in nature.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.