Answer:
²⁵ Mg = 10.00%
²⁶ Mg = 11.0%
Explanation:
Given that:
Magnesium ²⁴Mg has an abundance of 78.99%
Hence, (100 - 78.99)% = 21.01%
21.01% is the abundance of ²⁵ Mg and ²⁶ Mg
Suppose,
²⁵ Mg = x
²⁶ Mg = (21.01 - x)%
Then;
avg. atomic mass = 
where the avg. atomic mass = 24.3050
∴

2430.5 = 2440.46915 -0.9968 x
0.9968x = 2440.46915 - 2430.5
0.9968x = 9.96915
x = 9.96915/0.9968
x = 10.00%
∴ Recall that:
²⁵ Mg = x
²⁶ Mg = (21.01 - x)%
²⁵ Mg = 10.00%
²⁶ Mg = (21.01 - 10.00)%
²⁶ Mg = 11.0%
1. Silicon is in the same group and also has 4 valence electrons.
2. covalent
3. 1
4. Wood
6. 1s22s22p2
7. Covalent
Those questions were somewhat simple. Questions #5 and #8 I'm not certain of and if you have any kind of textbook or course material, it'd be beneficial to look at it. I hope you were able to figure out the answer to Question #4 was "Wood", otherwise your teacher must be slacking :P. I'll try to figure out the answers to #5 and #8 and let you know what I figured out.
Answer:
Elements only contain one type of atoms while compounds contain two or more types of atoms.
Explanation:
An example of an element is sodium --> Na (only Na atoms)
An example of a compound can be water --> H2O (contain H and O atoms)
*But the particles within a compound are all the same.
Answer: time on earth is measured by tracking earth's movement in relation to the axis
Explanation:
easy science