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:
420 miles
Explanation:
From the question given above, the following data were obtained:
Time = 3.5 hours
Speed = 120 mi/h
Distance =?
Speed is defined as the distance travelled per unit time. Mathematically, it is expressed as:
Speed = distance / time
With the above formula, we can obtain the distance travelled by the plane as follow:
Time = 3.5 hours
Speed = 120 mi/h
Distance =?
Speed = distance / time
120 = distance / 3.5
Cross multiply
Distance = 120 × 3.5
Distance = 420 miles
Thus, the distance travelled by the plane is 420 miles