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 : The standard enthalpy of formation of ethylene is, 51.8 kJ/mole
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The formation reaction of 
will be,
The intermediate balanced chemical reaction will be,
(1) 
(2) 
(3) 
Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equations, we get :
(1) 
(2) 
(3) 
The expression for enthalpy of formation of will be,
Therefore, the standard enthalpy of formation of ethylene is, 51.8 kJ/mole
6 inches of snowfall would be equivalent to 6/11 inches of water or 6/132 feet. So the volume of the equivalent amount of water on the roof is 150 ft. x 45 ft. x 6/132ft. = 306.8 cubic feet.
Since there are 907185 grams in a ton and 28316.8 mL in a cubic foot, 1.00 g/mL is equivalent to 0.0312 tons/cubic foot
Multiplying the two results gives 9.58 tons of snow.
Answer:
Explanation:
Oxidation state of Cr in CrPO₄
As a general rule, the algebraic sum of all the oxidation numbers of all atoms in a neutral compound is zero.
The compound above is in its neutral state and we sum all the oxidation numbers and equate to zero:
The oxidation number of P is -2
O is -2
Let the oxidation number of Cr be x:
x + (-2) + 4(-2) = 0
x -2-8 = 0
x -10 = 0
x = +10
For Cr in Cr₃(PO₄)₂
Using the same rule:
2(x) + 2[-2 + 4(-2)] = 0
2x + 2(-2-8) = 0
2x -20 = 0
x = +10
Metals are on the left side of the table and nonmetals are on the left with metalloids between them. And the noble gases are all in group 18 of the periodic table.
