2.4g
explanation: mass/volume=density
36/15=2.4
Answer:
a)= 0.025602u
b) = 23.848MeV
c) N = 1.546 × 10¹³
Explanation:
The reaction is
²₁H + ²₁H ⇄ ⁴₂H + Q
a) The mass difference is
Δm = 2m(²₁H) - m (⁴₂H)
= 2(2.014102u) - 4.002602u
= 0.025602u
b) Use the Einstein mass energy relation ship
The enegy release is the mass difference times 931.5MeV/U
E = (0.025602) (931.5)
= 23.848MeV
c)
the number of reaction need per seconds is
N = Q/E
= 59W/ 23.848MeV

N = 1.546 × 10¹³
The flow of Direct current (DC) is constant and flows in one direction. Most digital electronics make use of DC. Alternating current (AC) periodically flows in reverse and is mostly used to deliver power to houses, buildings and the like. With that alone, you can already rule out A, C and D.
The answer would then be B. constant, periodically reversing.
I uploaded the answer to a file hosting. Here's link:
tinyurl.com/wpazsebu