Answer: -
2.5 moles of calcium atoms are in 2.5 moles of calcium carbonate CaCO₃
Explanation: -
In order to solve such types of problems, the first step would be to write the chemical formula of the compound.
The chemical formula of calcium carbonate = CaCO₃
The chemical symbol of Calcium is Ca.
From the formula of calcium carbonate we can see that
1 mole of CaCO₃ has 1 mole of Ca
2.5 mole of CaCO₃ has 
= 2.5 mol of Ca.
∴2.5 moles of calcium atoms are in 2.5 moles of calcium carbonate CaCO₃
The sand on the beach cools down at night then the ocean is because the sand is on dry land.
Answer:
Explanation:
Entropy is measure of disorder so as we lower the temperature of gas , its entropy decreases .
Hence at - 200°C entropy of nitrogen will be less than that at - 190°C .
At freezing point ,
entropy of fusion = latent heat / freezing temperature
= .71 kJ / ( 273 - 210 )
= 710 / 63 J mol⁻¹ K⁻¹ .
= 11.27 J mol⁻¹ K⁻¹ .
entropy of fusion = 11.27 J mol⁻¹ K⁻¹ .