Q34 of 805 Page 156

The mass of one steel screw is 4.11g. Find the mass of one mole of these steel screws. Compare this value with the mass of the Earth (5.98 × 1024kg). Which one of the two is heavier and by how many times?

OR


In photosynthesis, 6 molecules of carbon dioxide combine with an equal number of water molecules through a complex series of reactions to give a molecule of glucose having a molecular formula C6H12O6. How many grams of water would be required to produce 18 g of glucose? Compute the volume of water so consumed assuming the density of water to be 1 g cm–3.

The mass of the steel screw = 4.11g


The weight of one mole of screw = 6.023 × 1023 × 4.11g


= 2.475 × 1021kg


Therefore,


Therefore, the mass of earth is 2.4 ×103 times the mass of screws or the earth is 2400 times heavier than one mole of screws.


OR


The photosynthesis reaction is given as :


6CO2 +6H2O → C6H12O6 + 6O2


1 mole of glucose needs 6 moles of water.


180 g of glucose needs (6×18)g of water i.e. 108g of water


1g of glucose will need g of water


18g of glucose needs × 18g of water = 10.8g


Density of water= 1g cm-3


Volume of water used= mass/density


= 10.8/1


= 10.8 cm3


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