Answer:
(a) 
(b) Rubidium
Explanation:
Hello,
This titration is carried out by assuming that the volume of base doesn't have a significant change when the mass is added, thus, we state the following data a apply the down below formula to compute the molarity of the base solution:

Solving for the molarity of base we've got:

Now, we can compute the moles of the base as:

(a) Now, one divides the provided mass over the previously computed moles to get the molecular mass of the unknown base:

(b) Subtracting the atomic mass of oxygen and hydrogen, the metal's atomic mass turns out into:

So, that atomic mass dovetails to the Rubidium's atomic mass.
Best regards.
Answer: Final temperature = 206∘C
Explanation:
Heat Energy is given as
q= mCΔT
ehere
q= Heat energy = 87.4J
m= mass=1.25g
C=specific heat c= 0.386Jg∘C) ,
ΔT = Change in temperate of which the final temperature= 25.0∘C
q= mCΔT
ΔT = q/mC
ΔT = 87.4/ 1.25 X 0.386=181.14∘C
But,
T final- T initial = ΔT
T final = T initial + ΔT
T final = 25.0∘C +181.14∘C=206.14∘C rounded to 206∘C
Idk bro i havent learned that yet
this equation is balanced.