An unknown monoprotic acid HA with a concentration of 0.050 M has a pH of 2.3. Which of the following can we conclude? A) It must be a strong acid.
B) It must be a weak acid.
C) A salt of its conjugate base would have no pH effect in solution.
D) Both A and C
E) None of the above

B) It must be a weak acid.

Explanation:

If HA is a strong acid

Now the pH value can be written as follows

But given that acid HA has 2.3 pH value.

Therefore we can say that HA is weak acid.

Thus the answer will be option (B).

B) It must be a weak acid.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current