Its air and water. if its multiple choice
Answer:
1-Pentene
Explanation:
If we look at all the options listed, we will notice that the rate of reaction of bromine with each one differs significantly.
For 1-pentene, addition of bromine across the double bond is a relatively fast process. It is usually used as a test for unsaturation. Bromine water is easily decolorized by alkenes.
Cyclohexane, heptane are alkanes. They can only react with chlorine in the presence of sunlight. This is a substitution reaction. It does not occur easily. A certain quantum of light is required for the reaction to occur.
For benzene, bromine can only react with it by electrophilic substitution in which the benzene ring is retained. A Lewis acid is often required for the reaction to occur and it doesn't occur easily.

is aluminium oxide (also called aloxide, aloxite and alundum). It is neither acid nor base. It has amphoteric nature meaning it can act as an acid with bases and as a base with acids. It neutralises them to salts.
Your answer is D rods and cones. Hope this helps!! :)
Viscosity is basically how thick a liquid is so pancake syrup would be the answer