7. D. 668 joules
8. B. 3 grams
<h3>Further explanation</h3>
Given
2 grams of water
6768 joules of energy
Required
Energy
Mass of water
Solution
The heat to change the phase can be formulated :
Q = m.Lf (melting/freezing)
Q = m.Lv (vaporization/condensation)
Lf=latent heat of fusion
Lv=latent heat of vaporization
7. phase change (ice to water)⇒Heat of fusion water=334 J/g
Q = 2 g x 334 J/g
Q = 668 J
8. phase change(water to vapor)⇒heat of vaporization water=2260 J/g
6768 J = m x 2260 J/g
m = 3 g
Kilograms and grams. They're both commonly used to measure mass.
Answer:
Silver and copper
Explanation:
Siliver
Electrical conductivity=62000000(s/m)
Boiling point=2162
Melting point=961.78
Phase=solid
Copper
Electrical conductivity=59000000(s/m)
Boiling point =2927
Melting point=1084.62
Phase=soild
Metals like gold, silver and copper are drawn into thin wire and are used in an electric circuit because of their high electrical conductivity
Mostly Siliver and copper are used since using gold is much expensive.
To know which is a better solvent between the two, one should know what will be the solute. It really depends on what type of solute you have. If the solute is polar then water is the better solvent for that type of solute. However, when the solute is a nonpolar substance then carbon tetrachloride is the better solvent.
Heterogeneous 'mixtures' (because they don't meet the definition of mixtures) are mixtures substances that aren't completely uniformly spread out. They haven't reacted with the solvent to become a solution.
Explanation: There are 2 types of heterogeneous solutions, A Colloid and a suspension.
Colloid: You can check if a mixture is heterogeneous by passing a light ray through it. This may cause the Tyndall effect (If the mixture is a colloid) when the Colloidal Heterogeneous mixture's particles are so small that they refract the beam of light and the path of light will be visible, like if you add 3 drops of milk in a glass of Water and shine a laser light through it. This is because the particles are too small to be seen by the unaided eye but big enough to scatter you laser light. However that particles won't settle down or will be separated by a filter paper due to particles' small size.
Suspension: A solution will be a solution when the particles of the Mixture is big enough to be seen by the unaided eye. Like if you mix sand and Water, the sand will eventually settle down due to Gravity. The mixture's solute will be big enough to pass through a filter paper.
