Answer:
in an atom or molecule, no two electrons can have the same four electronic quantum numbers. As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.
A calorimeter experiment is a set-up that provides insulation so that no heat escapes to the surroundings and all energy can be accounted for. It can be done at either constant volume or constant pressure. So, the answer to this is knowing the mass of water, the specific heat which is an empirical data, and the change in temperature which can be measured using a thermometer. This experiment could measure the mass of an unknown substance added or the specific heat of the substance or the calorimeter. <em>The answer is D.</em>
10. is C or gas and 11. is B liquid.
Here we have to compare the state of helium gas at STP and high temperature and low pressure.
At STP (standard condition of temperature and pressure) i.e. 273K temperature and 1 bar pressure. At STP helium gas will behave as a real gas.
At higher temperature and low pressure Helium will behave as an ideal gas.
The ideal gas conditions are developed on taking into account two factors: (i) the gas molecules are point of mass and having no volume. (ii) there is no existence of force of attraction between the molecules.
The deviation from ideal gas to the real gas depends upon the van der waals' interaction between the gas molecules. Now in low pressure and high temperature, we can ignore the volume and also the inter-molecular force of attraction. Thus the gas sample can behaved as ideal gas.
But at elevated pressure and low temperature i.e. STP the assumptions are not valid and it will behave as real gas.
To compute for the empirical formula, assume there is 100 grams of the compound. That means there is 40.28 g B, 52.2 g N and 7.53 g H. Convert the mass into moles using their molar masses:
40.28 g B * 1 mol/10.811 g = 3.725835 mol B
52.2 g N * 1 mol/14 g = 3.72857 mol N
7.53 g H * 1 mol/1 g = 7.53 mol H
Divide all the moles by the smallest amount which is 3.725835 mol.
B: 3.725835/3.725835 = 1
N: 3.72857/3.725835 = 1
H: 7.53/3.725835 = 2
Therefore, the empirical formula is BNH₂.
