A disc is a circle so the formula for the area is pie r^2. So plugging in the numbers bring in the answer of 18.53
Hi, did you ever get the answers?
A. carbon
b. the carbon atoms in diamond have a lot of strong covalent bonds with other carbon atoms. which are conjoined in a 3d structure. This means the ‘giant covalent structure’ of diamonds is very difficult to break, making diamonds very hard.
However, the carbon atoms in graphite have less covalent bonds, and graphite is structured in sheets of atoms with weak forces holding them together - this means these sheets can slide off easily and come apart from the structure. Therefore, graphite is very soft.
Air is a homogeneous mixture, and it is a mixture because it consists of <span>nitrogen, oxygen, carbon dioxide and other gases present in air. All of these gases mix together, and create something known as air. </span>
It's your hw so you really should understand it so you dont have to ask for help so I'll try to explain it the best I can.
1.SD (only one switch occurs, between fluorine and bromide)
2.DD (two things are switched, sulfate and nitrate)
3. D (One compound is broken up into smaller compounds)
4.C (The products of combustion are always h20 and co2)
5.DD (again, two things are switched, bromide and nitrate)
6.SD (In SDR, look for a lone molecule reacting with a compound)
7.S (two smaller compounds become one big compound)
8. D( A big compound is broken up)
9. DD (I think Its DD because two molecules were displaced)*not sure
10.DD(two molecules are displaced, phosphate and hydroxide)