Dmelting point 194 °C and boiling point 229 °C[1]
Z is a gas at 232 °C, so its boiling point is below 232 °C. Z is a solid at 179 °C, so its melting point is above 179 °C.
DMolecules in ammonia diffuse more quickly because they have a smaller mass than molecules of hydrogen chloride.[1]
The ring forms nearer the hydrogen chloride end, so the ammonia molecules travelled further. Lighter molecules diffuse faster.
AThe two gases remain mixed.[1]
Gas particles are in constant random motion, so a mixed gas stays mixed. It does not separate into layers.
C64 seconds[1]
Hydrogen chloride (Mr 36.5) is heavier than ammonia (Mr 17), so it diffuses more slowly and takes longer than 30 seconds.
DBoth the air and bromine particles move randomly.[1]
The particles of both gases are in constant random motion, so they diffuse until they are evenly mixed.
BX is neon and Y is fluorine[1]
Neon (Mr 20) is lighter than fluorine (Mr 38), so neon diffuses into the pot faster than fluorine diffuses out. The pressure in the pot rises and pushes the water level on the left side down.
The particles are vibrating and rotating about their fixed positions. [1]
They are very closely packed in an orderly manner. [1]
10 min [1]
Units are needed.
The forces of attraction between the particles at B are stronger than at C. [1]
The kinetic energy of the particles at B is lower than at C. [1]
80 °C [1]
The energy is absorbed to overcome the attractive forces between the molecules. [1]
The particles vibrate faster [1] about their fixed positions. [1]
Gases X and Y have a lower relative molecular mass than oxygen. [1]
The gases diffuse faster into the container filled with oxygen than the oxygen diffuses out of the container. [1]
The gases are then pushed down the tube, into the water, and escape as bubbles. [1]
Carbon dioxide or sulfur dioxide or nitrogen dioxide. Accept any gas with a higher relative molecular mass than oxygen. [1]
Chlorine has a higher relative molecular mass than the surrounding air, so it has a higher density than air. [1]
The comparison must be with air, not oxygen.
Bubbles would be produced faster in the beakers of gases X and Y, or water would rise faster up the tubes of gas Z and chlorine. [1]
As the temperature increases, the rate of diffusion increases. [1]
More thermal energy is converted into kinetic energy in the gas particles, so they move and diffuse faster. [1]
"More bubbles" is not accepted, because the idea of speed must be there.
The particles roll and slide over each other at first, and vibrate about fixed positions afterwards. [1]
The particles are closely packed and disorderly at first, and become closely packed and orderly. [1]
The liquid turns into a gas. [1]
Heat energy is absorbed and overcomes the forces of attraction between the particles, so the particles move further apart from each other. [1]