Basically there are only 2 unique different allele combinations that this organism can produce in their gametes for these traits. They are AB and Ab.
It’s gases. Gas particles are always moving around. They have no fixed position and so they have high energies. Density depends on how many particles are present, so if the gas particles move around freely there will be very less density, but if you compress them their particles will increase in number thereby increasing the density
You have rods and cones in your eye. Cones detect colour and fine detail. Rods are used for monochrome vision; usually, monochrome vision is used in poorly lit, dark environments. Rods and cones are both in the retina of the eye.
Cones = Colour. CC is a good mnemonic.