CHEM 1202 Chapter : Ascari 1

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azuremammoth471

15 Mar 2019

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True or false: guard cells expand when k+ gets pumped into the cells. 3: which two elements make up more than 90% of the dry weight of plants, carbon and nitrogen, oxygen and hydrogen, nitrogen and oxygen, oxygen and carbon, carbon and potassium. Answer: d: the bulk of a plant"s dry weight is derived from, soil minerals, co2, the hydrogen from h2 o, the oxygen from h2o, the uptake of organic nutrients from the soil. Answer: b: which soil mineral is most likely leached away during a hard rain, na, k, ca+, no3, h+ Pull up a root and find it has bulbs. Its benefitting from a mutualistic relationship btw bacteria and. Cut grass at ground level, come back and its just as tall. What caused it to grow: what is the mutualistic association between roots and fungi called, nitrogen fixation, rhizobium infection, mycorrhizae, parasitism, root hair enhancement.

Related Questions

1)The purpose of a catalyst in a PEM fuel cell is to: (check allthat apply)

a)create a more exothermic reaction (increase delta H)

b)increase the rate of reaction between O2 gas, H+ ions, andelectrons

c)provide energy to get the reaction started

d)act as enzymes to change the shape of the substrate

e)facilitate the production of water by lowering the activationenergy (E_a)

2)What element is commonly usedas the catalyst in proton exchange membrane (PEM) fuelcells?

a)gold

b)silver

c)platinum

d)iridium

3)What material is used as a support to make the catalyst in PEMfuel cells more efficient?

a)platinum

b)carbon

c)aluminum

d)titanium

4)What is one way researchers are trying to reduce the cost ofcatalysts in PEM fuel cells?

a)Replace the catalyst withanother metal

b)Lower the heat ofreaction (Delta H) for hydrogen and oxygen to form water

c)Use many nanoparticles of catalyst rather than a solidplate.

d)Raise the operating temperature to increase the rate ofreactions

5)Water can reduce the performance of PEM fuel cells becauseit

a)is a product of the reaction and accumulates on the catalystin excess over time.

b)dissolves the catalyst material.

c)absorbs heat, cooling the catalyst and making it lessefficient.

d)prevents CO from being oxidized.

6)Which of the materials listed below contaminate fuel-cells byaccumulating on the catalyst surface and limiting theirperformance?

a)water and CO

b)CO and CO2

c)sulfur and platinum

d)water and CO2

7)Which of the following is NOT a technological problem for fuelcell durability?

a)Fuel cell membranes develop holes over time, reducing theperformance of the system.

b)Catalysts and other metal components can corrode over time,limiting their performance.

c)There are few ways to test long-term properties of fuelcells.

d)Fuel cells must withstand thousands of hours of operating timeand crash impacts.

e)Delivering oxygen and hydrogen in appropriate amounts to thefuel cell membrane assembly has not been achieved.

8)The Earth's atmosphere is composed of about 21% Oxygen, 78%Nitrogen, and several other trace gasses. Included in the tracecomponents are small amounts of various gaseous hydrocarbons (suchas methane, CH4, and other carbon-containing molecules). Would COcontamination be a problem if a fuel cell ran exclusively on purehydrogen fuel (rather than methanol, for example)?

a)Yes, CO contamination would still result due to breakdown ofthe carbon support.

b)Yes, CO contamination can result due to impurities in the airsupply for the fuel.

c)No, pure H2 fuel is very exothermic. Any CO will be combustedby the fuel cell.

d)No, CO cannot form if carbon is not present in the hydrogensupply.

e)No, CO contamination would not matter because fuel cellscannot run on pure H2.

Show the calculation for determining the mass % of P2O5 in a fertilizer sample (starting from the MgNH4PO4.6H2O product mass)