The correct answers are as follows:
1. Aluminium will not be useful as food wrapping if it has a much lower melting point.
Aluminum is a metallic element that is malleable and soft, thus, it is easy to beat it into thin sheet, which are used to package food. The thin sheet is called aluminium foil. Aluminum is useful as a food wrapping because it has high temperature and thus, it does not react with food (the hotness of the packaged food is not capable of melting the metal). If the melting point of aluminium is lower, this implies that little temperature, such as the one from hot food will be able to melt aluminum foil, thus allowing the food to be contaminated with the metal.
2. When bleach react with fabric dye chemical change occur in the fabric.
The major element in bleach is chlorine. When laundry bleach is added to a fabric, the chlorine component of the bleach will react with the fabric dye and cause a colour change in the fabric. This type of change is called chemical change, because the original colour of the fabric can not be recovered.
3. Every substance has specific properties, which can be used to identify it. Two of such specific properties are melting point and boiling point. Melting point refers to a specific temperature at which a solid substance will melt while boiling point refers to a specific temperature at which a liquid substance will boil and turn to steam.
Water for instance has a boiling point of 100 degree Celsius. To find out if an unknown substance is water, one can determine the boiling point of such liquid. A boiling point of 100 degree Celsius will strongly signify that the substance is probably water. The same thing applies to melting point. If the specific boiling and melting point of substances are known, then they can be used to identify them.
Answer:
207.89g
Explanation:
The formula of the compound is:
Fe₂S₃
Find the molar mass of the compound;
Atomic mass of Fe = 55.845g/mol
S = 32.065g/mol
Now;
Molar mass of Fe₂S₃ = 2 (55.845) + 3 (32.065)
= 207.89g
Answer:
C
Explanation:
The oxidation number of Sulphur in SO4^2- is;
x + 4(-2) = -2
x - 8 = -2
x = -2 + 8
x = 6
Now,
the oxidation number of sulphur in H2SO3 is
2 (1) + x + 3(-2) = 0
2 + x -6 = 0
-4 + x = 0
x = 4
Hence, the oxidation number of sulphur changed from +6 to +4 which signifies gain of two electrons as shown in option C.
An Endothermic change is a process in which there is absorption of energy.
-Condensation is the transformation from a gas to a liquid. So the water molecules releases energy while condensing, so condensation is exothermic (opposite of endothermic, it's the release of energy)
-Vaporization is the transformation from a liquid to a gas. When you heat water to evaporate it, you're giving energy to the water molecules. And when they absorb this energy, they transform to a gas. Which means that Vaporization is endothermic.
-Deposition is the transformation from gas directly to solid without passing by the liquid phase. Same as the condensation, but the water molecules release even more energy to directly become Solid. So deposition is exothermic.
-Freezing is the transformation from a liquid to a solid. During this phase, water molecules releases energy to its surrounding. So freezing is exothermic.
We can conclude that Vaporization is endothermic, because it's absorbing energy to transform from liquid to gas, while condensation, deposition and freezing are exothermic because they release energy to transform.
Hope this Helps! :)