Answer: The given statement is false.
Explanation:
Precipitation reaction is defined as the chemical reaction in which two aqueous solution upon mixing together results in the formation of an insoluble solid.
For example, 
Here AgCl is present in solid state so, it is the precipitate.
But it is not necessarily true that two aqueous solutions will always result in the formation of a precipitate.
For example, 
Hence, we can conclude that the statement precipitation reactions always occur when two aqueous solutions are mixed, is false.
Answer:
The force that keeps the planets in orbit is gravity.
Answer:
No. 3 lithium
Explain that lithium has 3 protons and 3 electrons. There are 2 electrons on the first energy level and 1 electron on the second
No. 4 Hydrogen (H) and helium (He) have a valence shell containing one and two electrons respectively. They make up the first period (row) of the periodic table. Their valence electron/s are in the first energy level (n=1) , as is denoted by 1s1 and 1s2 .
<em>That</em><em>'</em><em>s</em><em> </em><em>all</em><em> </em><em>i</em><em> </em><em>dont</em><em> </em><em>know</em><em> </em><em>if</em><em> </em><em>this</em><em> </em><em>is</em><em> </em><em>right</em><em> </em><em>though</em><em>.</em><em> </em>