Answer: 2. cannot be an element.
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper 
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: methane 

Thus as it can be decomposed into its constituent elements, it is a compound.
Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present.
Thus methane cannot be an element.
Answer:
602200000000000000000000
Explanation:
move the decimal place over 23 places to the right
Answer:
8.547 x 10⁴disintegrations per second
Explanation:
To calculate the disintegrations per second as -
Given ,
2.31 μCi of sulfur -35 .
Since ,
1 Ci = 3.7 * 10 ¹⁰ Bq
1 μCi = 10 ⁻⁶ Ci
Hence ,
conversation is done as follows -
2.31 ( 1 * 10⁻⁶) * ( 3.7 * 10¹⁰)
= 8.547 x 10⁴
Hence ,
8.547 x 10⁴disintegrations per second , the sample undergo for it to be brand new .
Answer:
A fluorine atom has nine protons and nine electrons, so it is electrically neutral. If a fluorine atom gains an electron, it becomes a fluoride ion with an electric charge of -1.