I believe it becomes less dense, bc when you heat something it’s molecules spread further apart.
Answer:
Chemical change.
Explanation:
When it is heated it decomposes into mercury and oxygen gas. The mercury oxide reactant becomes the silver color of mercury. Hence, a color change can be noticed throughout the reaction.
Explanation:
In liquids, the molecules are held by less strong intermolecular forces of attraction as compared to solids. Due to which they are able to slide past each other. Hence, they have medium kinetic energy.
In gases, the molecules are held by weak Vander waal forces. Hence, they have high kinetic energy due to which they move rapidly from one place to another leading to more number of collisions.
So, when at 298 K and 1 atm 
exists in liquid state and 
exists as a gas then it means there occurs strong force of attraction between the molecules of due to which it exists in liquid form.
Thus, we can conclude that at 298 K and 1 atm, bromine is a liquid with a high vapor pressure, whereas chlorine is a gas. This provides evidence that, under these conditions, the forces among 
molecules are greater than those among 
molecules.
Answer:
Mass of KCL = 218 grams.
Explanation:
Step 1: calculate the heat that must be absorbed(q).
Heat that must be absorbed(q) is calculated as follows:
q= m c (T2-T1).
q = 750g (4.18 J/gC)(20-4 C) = 5.016X10^4 J = 50.16 kJ
Step 2: we determine moles of KCL as follows:
Moles KCl = 50.16 kJ / 17.2 kJ/mol = 2.92 moles.
Step 3: calculate mass of KCL:
Mass of KCl = 2.92 mol X 74.55 g/mol = 218g.
Therefore, 218 grams of KCL would have to be dissolved into 750 g of 20.0°C H2O to produce the solution.
