1-5) How to create the table:
create table planets (name char(8) not null, NumMoons tinyint default 0, type enum("gas", "rocky"), LengthOfYear float, key(name));
How to insert a value:
insert into planets values ("mercury", 0, "rock", 0.24);
The table description
mysql> describe planets;
+--------------+---------------------+------+-----+---------+-------+
| Field        | Type                | Null | Key | Default | Extra |
+--------------+---------------------+------+-----+---------+-------+
| name         | char(8)             |      | MUL |         |       |
| NumMoons     | tinyint(4)          | YES |     | 0       |       |
| type         | enum('gas','rocky') | YES |     | NULL    |       |
| LengthOfYear | float(10,2)         | YES |     | NULL    |       |
+--------------+---------------------+------+-----+---------+-------+
4 rows in set (0.00 sec)

6)
mysql> select name, area, pop from nations where pop > 20000000 order by area asc limit 1;
+--------+-------+-------------+
| name | area | pop |
+--------+-------+-------------+
| Taiwan | 13830 | 22113250.00 |
+--------+-------+-------------+
1 row in set (0.00 sec)

7)
mysql> select code from nations where name = "kenya" or name = "tanzania";
+------+
| code |
+------+
| ke |
| tz |
+------+
2 rows in set (0.00 sec)

mysql> select * from borders where Code1 = "ke" and Code2 = "tz";
+-------+-------+--------+
| Code1 | Code2 | Length |
+-------+-------+--------+
| ke | tz | 493.52 |
+-------+-------+--------+
1 row in set (0.00 sec)

8)
mysql> select sum(pop*percent/100) Adherents, Religion from nations, Religions where nations.code = Religions.code group by religion order by Adherents desc;
+-----------------+------------+
| Adherents       | Religion   |
+-----------------+------------+
| 1561934339.2405 | Christian |
| 1303022569.0727 | Muslim     |
| 855202424.7858 | Hindu      |
| 384832831.2927 | Buddhism   |
| 272508227.6499 | Orthodox   |
| 136172588.9950 | indigenous |
|   11228498.6164 | Jewish     |
+-----------------+------------+
7 rows in set (0.09 sec)

9)
mysql> select pop * percent / 100, name, religion from Religions, nations where Religions.code = nations.code and name = "Germany";
+---------------------+---------+-----------+
| pop * percent / 100 | name    | religion |
+---------------------+---------+-----------+
|       59102899.2000 | Germany | Christian |
|        1395485.1591 | Germany | Muslim    |
+---------------------+---------+-----------+
2 rows in set (0.00 sec)

10)
mysql> select name from nations where code = "up";
+---------+
| name |
+---------+
| Ukraine |
+---------+
1 row in set (0.00 sec)

11)
mysql> select count(name) from nations where map = "Africa" group by map;
+-------------+
| count(name) |
+-------------+
|          58 |
+-------------+
1 row in set (0.00 sec)
OR
mysql> select name from nations where map = "Africa";
+-------------------------------+
| name                          |
+-------------------------------+
| Algeria                       |
(lots more)
| Swaziland                     |
| Zambia                        |
| Zimbabwe                      |
+-------------------------------+
58 rows in set (0.02 sec)