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Answer:
a solution of acetic acid and sodium acetate
Explanation:
A buffer solution is defined as a solution which resist a change in pH when small quantity of a strong acid or a strong base are added. A buffer solution is made up of mixture of a weak acid and its conjugate base or a mixture of a weak base and its conjugate acid.
Acetic acid is the only option because it is a weak acid with a corresponding conjugate base, acetate. Unlike a solution of sulfuric acid and sodium sulfate in which the sulfuric acid is a strong acid which doesn’t qualify it to be a buffer solution. The remaining options have different acid compounds paired together which makes them invalid too.
<u>Answer:</u> The mass of sample A after given time is 99.05 g.
<u>Explanation:</u>
All the radioactive reactions follows first order kinetics.
The equation used to calculate half life for first order kinetics:

We are given:

Putting values in above equation, we get:

Rate law expression for first order kinetics is given by the equation:
![k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B2.303%7D%7Bt%7D%5Clog%5Cfrac%7B%5BA_o%5D%7D%7B%5BA%5D%7D)
where,
k = rate constant = 
t = time taken for decay process = 84.2 s
= initial amount of the reactant = 250 g
[A] = amount left after decay process = ?
Putting values in above equation, we get:
![0.011s^{-1}=\frac{2.303}{84.2s}\log\frac{250}{[A]}](https://tex.z-dn.net/?f=0.011s%5E%7B-1%7D%3D%5Cfrac%7B2.303%7D%7B84.2s%7D%5Clog%5Cfrac%7B250%7D%7B%5BA%5D%7D)
![[A]=99.05g](https://tex.z-dn.net/?f=%5BA%5D%3D99.05g)
Hence, the mass of sample A after given time is 99.05 g.
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.