The independent variable would be the variable in the research that is being manipulated by the researcher. In this case, it would be amount of food as it is what is being manipulated and changed in the research design. The dependent variable would be the variable that is being studied so, for this case, it would be the weight gain of the mice. The constants are the factors that might affect the dependent variable but is held constant or the same by the researcher throughout the experiment. These are the size of cage, amount of water, amount of sunlight, temperature and the exercise wheel.
The least dense layer of the earth is the crust.
Your answer would be an Element can't be separated into simpler substances or converted into another substance by chemical process.
Hope that helps!!!
The formula for molality---> m = moles solute/ Kg of solvent
the solute here is NH₃ because it's the one with less amount. which makes water the solvent.
1) let's convert the grams of NH₃ to moles using the molar mass
molar mass of NH₃= 14.0 + (3 x 1.01)= 17.03 g/ mol
15.0 g (1 mol/ 17.03 g)= 0.881 mol NH₃
2) let's convert the grams of water into kilograms (just divide by 1000)
250.0 g= 0.2500 kg
3) let's plug in the values into the molality formula
molality= mol/ Kg---> 0.881 mol/ 0.2500 kg= 3.52 m
= 
= 9.95 mL
x 100 
x 100 = 0.5 % error