A mixture is a system that is made up of two or more substances which are not combined chemically. A pure substance is a system that only has one substance. The following are classified as:
1.water : pure substance
<span>2.blood : mixture</span>
<span>3.the oceans : mixture</span>
<span>4.iron : pure substance
5.brass : mixture</span>
<span>6.uranium : pure substance</span>
<span>7.wine : mixture</span>
<span>8.leather : mixture</span>
<span>9.table salt (NaCl) : pure substance</span>
Answer:

Explanation:
Nitrogen has the atomic number = 7
So, No. of electrons = 7
<u><em>Electronic Configuration:</em></u>

<u>Remember that:</u>
s sub shell holds upto 2 electrons while p sub shell upto 6
The two compounds present
in unpolluted air are carbon dioxide and water. You may think that carbn
dioxide is a greenhouse gas, yes it is and at the same time not. There animals
in the earth that produces carbon dioxide into the atmosphere, the carbon
dioxide too, is also need for plan respiration.
Q1. Chemical, Physical, Physical, Physical
(l am not 100% sure about the 4th answer)
Q2. All of the above