The number of oxygen atoms is in 5.00 g of sample of sodium dichromate, Na₂Cr₂O₇ is 1.125 x 10²³ atoms.
<h3>What is sodium dichromate?</h3>
Sodium dichromate is an inorganic compound. It is sued in tanning and mental illness.
The molar mass of sodium = 23 gm
The molar mass of Cr = 51.99 gm
The molar mass of oxygen = 16 gm
Molar mass of Na₂Cr₂O₇ = 2(23) + 2(51.99) + 7(16) = 261.98 gm
Number of moles in 7 gm = mass / molar mass = 7 / 261.98 = 0.0267 moles
1 mole of Na₂Cr₂O₇ contains 7 moles of oxygen, therefore:
The number of moles of oxygen in 0.0267 moles = 0.0267 x 7 = 0.1869 moles
Thus, the number of atoms = 0.1869 x 6.02 x 10^23 = 1.125 x 10²³ atoms.
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Answer: Option (b) is the correct answer.
Explanation:
When useful energy is conserved then this conservation is known as energy conservation.
For example, when lights of a room are switched on where no one is sitting then on switching off the lights we are conserving wastage of electricity.
Thus, we can conclude that out of the given options, the statement energy resources can be conserved by turning off lights when they are not in use is true.