Answer:
a. an increase in the mass on the spring.
Explanation:
An increase in the mass on the spring will increase the period of an oscillating spring mass system.
Mathematically, the period of an oscillating spring mass system is given by the formula;
T = 2π √(m/k)
Where;
T is the period.
m is the mass of the spring.
k is the spring constant.
Hence, the mass of a spring is directly proportional to the period of oscillation of the spring.
This ultimately implies that, as the mass of the spring increases, the period of oscillation will increase. Similarly, the period of oscillation will decrease with an increase in the spring constant.
D. both b. and c. Obviously adding more gas but reducing the volume because of the limited space in the container.
Answer:

Explanation:
For n-=1 state hydrogen energy level is split into three componets in the presence of external magnetic field. The energies are,
,
,

Here, E is the energy in the absence of electric field.
And
are the highest and the lowest energies.
The difference of these energies

is known as Bohr's magneton.
B=2.5 T,
Therefore,

Now,

Therefore, the energy difference between highest and lowest energy levels in presence of magnetic field is 