False. At equilibrium, the rate of forward reaction is equal to the rate of backward reaction. The net concentration of both products and reactants won't change, but the reactions still take place.
Answer: Transition from X to Y will have greater energy difference.
Explanation: For studying the energy difference, we require Planck's equation.

where, h = Planck's Constant
c = Speed of light
E = Energy
= Wavelength of particle
From the equation, it is visible that the energy and wavelength follow inverse relation which means that with low wavelength value, energy will be the highest and vice-versa.
As electron A falls from X-energy level to Y-energy level, it releases blue light which has low wavelength value (around 470 nm) which means that it has high energy.
Similarly, Electron B releases red light when it falls from Y-energy level to Z-energy level, which has high wavelength value (around 700 nm), giving it a low energy value.
Energy Difference between X-energy level and Y-energy level will be more.
As the gas cools it condenses and becomes a liquid its atoms also become smaller
Answer:
30.33L
Explanation:
Using Boyle's law which states that the volume of a given mass of gas is inversely proportional to the pressure, provided temperature remains constant and Charles law states that the volume of a given mass of gas is directly proportional to the temperature provided the pressure remains constant
P1V1/T1 = P2V2/ T2
P1 = 78atm, V1 = 21L , T1 = 900K
P2 = 45atm, V2 = ? , T2 =750K
78× 21 / 900 = 45×V2 / 750
1638/900 = 45 V2 / 750
1638×750 = 900×45V2
1228500 = 40500V2
Divide both sides by 40500
1228500÷40500= V2
V2 = 30.33L
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When it comes to physical changes like phase changes, there are two types of heat energy: sensible heat and latent heat. Sensible heat is the heat absorbed/released when you heat the substance but it doesn't change phase. An example would be heating lukewarm water. The substance is liquid all throughout. Latent heat, on the other hand, is the heat absorbed/released when there is a phase change. An example would be boiling water, because it changes liquid to vapor.
Hence, for freezing liquid, you use the latent heat, specifically the heat of fusion. The answer should be
2.5 g * (1 mol/18.02 g) * 6.03 kJ/mol = 0.84 kJ/mol
The answer is not in the choices. You only use Hvap if you boil water.