The fundamental force underlying all chemical reactions is
a) gravitational.
b) nuclear.
c) centripetal.
d) electrical.
e) none of these.

i think it because equal matrices have equal dimensions, only square matrices can be symmetric. for all indices and . every square diagonal matrix is symmetric, since all off-diagonal elements are zero. in linear algebra, a real symmetric matrix represents a self-adjoint operator over a real inner product space.

compass can be used day and night, cloudy or sunny