The solid having the highest melting point is Na₂O and the correct option is option 2.
The melting point of a solid is a measure of the temperature at which it changes from a solid to a liquid state. It is influenced by the strength of the intermolecular forces between the particles in the solid.
Na₂O(s), which is sodium oxide, has the highest melting point among the given options. This is because Na₂O is an ionic compound composed of positively charged sodium ions (Na⁺) and negatively charged oxide ions (O²⁻). Ionic compounds have strong electrostatic forces of attraction between the ions, known as ionic bonds. These bonds require a significant amount of energy to break, resulting in a high melting point.
H₂O(s) (water ice) has a lower melting point because it is a molecular compound held together by weaker hydrogen bonds.
SO₂(s) (sulfur dioxide) and CO₂(s) (carbon dioxide) are molecular compounds with weaker intermolecular forces, such as London dispersion forces, resulting in lower melting points compared to ionic compounds.
Thus, the ideal selection is option 2.
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56 Explain why the total thermal energy of a sample containing 22.2 grams of NaNO3 dissolved in 200. grams of water at 20.°C is greater than the total thermal energy of a sample containing 11.1 grams of NaNO3 dissolved in 100. grams of water at 20.°C. [1]
57 Compare the boiling point of a NaNO3 solution at standard pressure to the boiling point of water at standard pressure. [1]
B. c-14
C. u-235
D. u-238
Answer:
C. U-235
Explanation:
A fission reaction is one in which an unstable radioisotope breaks down into smaller nuclei when bombarded with energetic particles.
The highly unstable isotope that is often used in fission reactions is U-235. When bombarded with neutrons that atom breaks down to form krypton and barium along with the release of a large amount of energy. The reaction is given as:
₉₂U²³⁵ + ₀n¹ → ₃₆Kr⁸⁹ + ₅₆Ba¹⁴⁴ + 3₀n¹ + 210 Mev energy