Love the toradora pfp, also the answer to your question is...
answer: from newtons second law of motion,
F=ma hence,
F=20N
m=5kg so,
20=5×a
a=4m/s^2
C. The particles that make up material A have more mass than the particles that make up material B.
Answer: 2, you divide the value by 1000, so... 2000/1000 = 2.
Option 4. ratio of electrons to protons
Isotope that has atomic number of 82 is stable. An element that has an atomic number ∠82 more stable except Tc and Pm. Also there is the concept that isotopes consisting a combination of even-even,even-odd,odd-even, and odd-odd are all stable. Many isotopes with no magic numbers of nucleons are stable