1) d
2) b because the independent variable is the thing you change/control in an experiment
3) c because the dependent variable is the thing being measured in an experiment
4)hmm it might be d, as c and a are both correct as different sized feeders would make it an unfair test and different types of food would as well
5) c
6) a
7) b obviously because if he activated them at different times then the ones activated last would have an advantage
Answer:
False
Explanation:
Half life is the time period at which the concentration of the radioactive substance in decay reduced to half.
<u>Thus, if the hydrogen-3 has gone 2 half lives, it means that it has first reduced to its half and then again the half of what it was, i.e. 1/4</u>
Thus, after two successive half-lives, the concentration must be 1/4 of the initial concentration and hence, the statement is false.
Answer: One formula unit of NaCl consists of one cation, whose chemical symbol is 
and one anion whose chemical symbol is 
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
The cation is formed by the metal sodium which forms and the anion is formed by non metal chlorine which forms .
For a formula unit of sodium chloride, the charges have to be balanced , thus the valencies of ions are exchanged and the neutral compound result. Thus
and combine to form neutral 
The mass percentage is 15.1465%.
I would say 3, but I’m not 100% sure
