The mass of a star can be determined by studying D) binary star systems.
Although there may be other ways to determine the mass of a star, this is the most common one which is widely used all over the world when it comes to measuring objects in the universe.
The answer is true. It is because the activated sludge
process made use of the aeration in which air being mixed with a substance
together with a bacteria and protozoa that is in a biological floc that will
help treat the wastewater.
By tar, I think you mean nicotine. (I Hope). It affects the nerve signals that regulate breathing.
One
substance, other than the secretions from nerve cells, that is used in cell
communication are hormones.
<span>
To
add, <span>a hormone is any member of a class of signaling
molecules produced by glands in multicellular organisms that are transported by
the circulatory system to target distant organs to regulate physiology and
behaviour.</span></span>
