Answer:
hair is a physical change.
Cooking is a physical and chemical change.
Ice cream melting in the sun is a physical change.
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Answer:
The answer is B) The law of conservation of energy.
Explanation:
This is the answer because energy cannot be created or be destroyed in a isolated system. The second law as well states that the entropy of any isolated system always increases.
<u>Answer: </u>The concentration of 
in the solution is 
<u>Explanation:</u>
pH is defined as the negative logarithm of hydrogen ion concentration present in the solution.
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)
.....(1)
We are given:
pH of solution = 2.5
Putting values in equation 1, we get:
![2.5=-\log [H^+]](https://tex.z-dn.net/?f=2.5%3D-%5Clog%20%5BH%5E%2B%5D)
![[H^+]=10^{-2.5}](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D10%5E%7B-2.5%7D)
![[H^+]=3.16\times 10^{-3}M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D3.16%5Ctimes%2010%5E%7B-3%7DM)
Hence, the concentration of in the solution is
<u>Answer:</u> The change in enthalpy for the given system is -642.8 kJ/mol
<u>Explanation:</u>
To calculate the change in enthalpy for given Gibbs free energy, we use the equation:
where,
= Gibbs free energy = -717.5 kJ/mol = -717500 J/mol (Conversion factor: 1 kJ = 1000 J)
= change in enthalpy = ?
T = temperature = 337 K
= change in entropy = 221.7 J/mol.K
Putting values in above equation, we get:
Hence, the change in enthalpy for the given system is -642.8 kJ/mol
Answer:
1-b
2-weaker(option is incorrect)
3-a
Explanation:
1-b because iodine is more electronegative because of this negative on iodine will be more stable as negative charge on more electronegative element is more stable.
2-weaker as size of Te (Tellurium) is greater than S (sulphur) so bond length of H-Te is larger than H-S and therefore bond energy will be lesser and can easily give hydrogen in case of H-Te. as bond energy is inversly proportional to bond length.
3-a hydrogen has more negative electron affinity so hydrogen will have -1 charge and it will behave as a electron donar atom that is basic not acidic hence NaH is not acidic.
