Answer:
V
Explanation:
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convection is unspecified, convection due to the effects of thermal expansion and buoyancy can be assumed. Convection may also take place in soft solids or mixtures where particles can flow.
I would say they design and build things.
Answer:
Describe how a sample of copper chloride crystals could be made from copper carbonate and dilute hydrochloric acid. Add excess copper carbonate to hydrochloric acid in a beaker, stirring until there is no further reaction. Filter the mixture to remove the remaining copper carbonate, then heat the remaining solution to the point of crystallisation.
Explanation: Hope this is right.
So if we use the equation:
→ 
We can then determine the amount of 
needed to produce 208 kg of methanol.
So let's find out how many moles of methanol 208 kg is:
Methanol molar weight = 32.041g/mol
So then we can solve for moles of methanol:
So now that we have the amount of moles produced, we can use the molar ratio (from the balanced equation) of hydrogen and methanol. This ratio is 2:1 hydrogen:methanol.
Therefore, we can set up a proportion to solve for the moles of hydrogen needed:
So now that we have the number of moles of 
that are produced, we can then use the molar weight of hydrogen to solve for the mass that is needed:
Therefore, the amount of diatomic hydrogen () that is needed to produce 208kg of methanol is 
g.
