Answer:
Among Na ,K , Pb , Li , The atom which does not react with water is :
<u>Pb</u>
Explanation:
Li : Reacts slowly with water
Na ,K : Reacts vigorously with water
Pb : It does not reacts with water because :- Pb oxidize in presence of atmospheric oxygen to form lead oxide (PbO) . this PbO form a layer over the surface of Pb and make it inert to water.
Answer:
1. Exothermic.
2. -1598 kJ.
Explanation:
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1. In this case, according to the reaction, we can infer that 799 kJ of energy are evolved (given off, released) it means that the enthalpy of reaction is negative as the reactants have more energy than the products; which means this is an exothermic reaction.
2. Here, as we know that the enthalpy of reaction is -799 kJ/mol, we can compute the q-value as shown below, considering the reacted 2 moles of solid iron:

Which means that 1598 kJ of energy are evolved when 2 moles of solid iron react.
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Answer:
3.37 × 10²³ molecules
Explanation:
Given data:
Mass of C₆H₁₂O₆ = 100 g
Number of molecules = ?
Solution:
Number of moles of C₆H₁₂O₆:
Number of moles = mass/molar mass
Number of moles = 100 g/ 180.16 g/mol
Number of moles = 0.56 mol
Number of molecules:
1 mole contain 6.022 × 10²³ molecules
0.56 mol × 6.022 × 10²³ molecules /1 mol
3.37 × 10²³ molecules