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: 
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
Thus in the reactants, there are 2 atoms of hydrogen and 2 atoms of iodine .Thus there has to be 2 atoms of hydrogen and 2 atoms of iodine in the product as well. Thus a coefficient of 2 is placed in front of HI.
The balanced chemical reaction is:
Refer to the attachment for answer.
SOME EXTRA INFORMATION:
Bromo is used for Bromine (Br)
Chloro is used for Chlorine(Cl)
'ene' represents double bond between carbon atoms.
'ol' is used for alcohol
HOPE IT IS USEFUL
Answer:
—COOH
Explanation:
—COOH, acid group, containing 3 elements, C, carbon, O, oxygen, and H, hydrogen.
