Answer:
1.89mol
Explanation:
The entropy change during free expansion is express as

Where S is the entropy of the system,
n is the amount of mole
R is the gas constant = 8.314 and
V is the volume occupied at the initial and final stage
since the process is n adiabatic free expansion, the entropy of the system is constant. Hence we can re-write the equation as

where the
and 
and
Now if we substitute in values we arrive at

Answer: The double stroke roll works just like the single stroke roll - it's played in a sequence of alternating strokes (roll). But instead of having one stroke per hand you'll have two, as shown on the sheet music below. You can use full wrist turns to play each stroke of the double stroke at slower speeds.
Explanation: hope this helps!
Induced electromotive force
Answer:
[a]
F=ke
E= 5/100=0.05m, m=2kg, F=mg[2x9.8]=19.6N
Spring constant[K] =F/e
K=19.6/0.05
K=392N/m