What material would be the best choice for the support beams of a building? wood steel a thermoset kevlar

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Chemistry worksheet - i am not sure what they are asking for exactly?

For the reaction c6h14(g) & longrightarrow; c6h6(g) + 4h2(g), δp(h2)/δt was found to be 2.5 x 10-2 atm/s, where δp(h2) is the change in pressure of hydrogen. determine δp(c6h14)/δt for this reaction at the same time.