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