D, because C12 means there's 12 atoms of carbon.
Answer:
C. Lose three electrons to have a full outer shell
Explanation:
Al is in Group 13 of the Periodic Table, so it has three valence electrons.
It must either lose three electrons or gain five to achieve a stable octet.
It is easier to lose three electrons than it is to gain five, so Al loses three electrons.
D. is wrong, for the same reason.
A. is wrong. If Al lost three electrons, it would be breaking into a stable inner shell.
C. is wrong. Al is a metal, so it will lose electrons in a reaction.
The answers are
The age of the oldest stars
How fast distant galaxies are moving away from us
Patterns of background radiation.
Explanation:
The Astronomers calculate the age of the universe by looking for oldest stars, and by measuring the rate of expansion of the universe and back to big bang.
The Astronomers used the techniques like the age of oldest stars, how fast the distant galaxies are moving away from us, patterns of background radiation and along with the Big Bang as reference point, they estimate that the universe may be approximately 12 billion years old.
Answer:
How the relative density of a substance is related to the density calculate the density of iron if its relative density is 2 and a density of water is 2gcm -3
R.d= relative density of substance/ relative density of water
R.d= 2/2
R.d= 1gcm-3
Explanation:
Oil makes it impossible for fur-bearing mammals to insulate<span>, this leaves them unprotected from the harsh elements out in the water. Birds and mammals will die from hypothermia without the ability to insulate from the freezing water.
I hope this helps you! :-)</span>
