Answer:
Exa homogeneous mixtureplanation:
solid iron at 300°C
liquid iron at 1600°C
liquid iron at 1800°C
Answer:
The answer is D
Explanation:
b. no energy is destroyed in the process.
c. energy is created in the process.
d. some amount of energy cannot be accounted for.
Energy of a system is conserved always but it can be converted to other forms . By this conversion no energy is destroying or creating. Thus, option b is correct.
What law of conservation of energy?
According to the law of conservation of energy, energy can neither be created nor be destroyed. However, it can be transformed into other forms. For instance, in light bulb, electrical energy is converting to light energy and heat energy.
Similarly, in fan and motors, electrical energy is converting to mechanical energy and in thermal power plants, thermal energy is converting to electrical energy.
In all of these cases, no amount of energy is destroying or creating. The already existing energy is transforming to various other forms.
Similarly when tow objects in contact exchange energy by mixing or any force, the energy lost from a system will be equal to the energy gained by the second system. Therefore, the total energy is conserved.
To find more on energy transformation, refer here:
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The law of conservation of energy states that when one form of energy is converted into another, no energy is destroyed in the process. The answer is letter B. Energy cannot be created nor destroyed, it can only be converted from one form into the other.
The question is incomplete, this is the complete question;
In the process of attempting to characterize a substance, a chemist makes the following observations. Which are physical properties and which are chemical properties?
(a) The substance is a silvery white, lustrous metal.
(b) The substance melts at 649 ∘C
(c) The substance boils at 1105 ∘C.
(d) The density of the substance at 20 ∘C is 1.738 g/cm³.
(e) The substance burns in air, producing an intense white light.
(f) The substance reacts with chlorine to give a brittle white solid.
(g) The substance can be pounded into thin sheets or drawn into wires.
(h) The substance is a good conductor of electricity.
Answer:
(a) Physical
(b) Physical
(c) Physical
(d) Physical
(e) Chemical
(f) Chemical
(g) Physical
(h) Physical
Explanation:
(a) The substance is a silvery white, lustrous metal - is appearance which is physical.
(b) The substance melts at 649 ∘C metling point is a physical measurement
(c) The substance boils at 1105 ∘C boiling point is a physical measurement
(d) The density of the substance at 20 ∘C is 1.738 g/cm3 how heavy a substance is,is physical.
(e) The substance burns in air, producing an intense white light. Burning is a chemical change. It is a reaction of a substance with oxygen
(f) The substance reacts with chlorine to give a brittle white solid. This is a chemical reaction as the question says.
(g) The substance can be pounded into thin sheets or drawn into wires. Ductility is a physical change, the substance remains chemically unchanged
(h) The substance is a good conductor of electricity. Any conductivity is physical, the substance remains chemically unchanged
The substance in question is likely a pure metal, more specifically Magnesium, because of its documented properties such as lustrous appearance, ability to be drawn into wires, and high electrical conductivity. Its properties like high melting and boiling points and its reactions suggest it could be from Group 1, but its ability to be formed into sheets and wires and its high conductivity suggest it's not an ionic compound like sodium chloride.
The substance described in the question seems to be an example of pure metal due to the properties like lustrous appearance, ability to be drawn into wires or pounded into sheets, and high conductivity of electricity. However, some of the properties like reaction with chlorine, production of intense white light upon burning in air, and its high melting and boiling points suggest that it could be a Group 1 element such as sodium or potassium, which are known for these characteristics. Coupled with information of its density and its ability to form brittle white solid upon reaction with chlorine, it seems to likely be Magnesium, a silvery-white lustrous metal.
Furthermore, ionic compounds like sodium chloride have high melting and boiling points, conduct electricity when molten, and ions are freed to move allowing conductivity. However, such compounds, unlike pure metals, cannot be drawn into wires or pounded into sheets and are usually brittle solids, which would make it less likely that the substance in question is an ionic compound.
The most confident identification will be based on the substance's observed physical and chemical properties and their comparison to known properties of pure metals and ionic compounds.
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