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
After 25 days, it remains radon 5.9x10^5 atoms.
Half-life is the time required for a quantity (in this example number of radioactive radon) to reduce to half its initial value.
N(Ra) = 5.7×10^7; initial number of radon atoms
t1/2(Ra) = 3.8 days; the half-life of the radon is 3.8 days
n = 25 days / 3.8 days
n = 6.58; number of half-lifes of radon
N1(Ra) = N(Ra) x (1/2)^n
N1(Ra) = 5.7×10^7 x (1/2)^6.58
N1(Ra) = 5.9x10^5; number of radon atoms after 25 days
The half-life is independent of initial concentration (size of the sample).
More about half-life: brainly.com/question/1160651
#SPJ4
Chemistry is the study of the composition of matter and the ways in which matter interacts, combines, and changes under certain conditions. Although not as fundamental as physics, chemistry is a very basic and broad science. It helps us explain bodily interactions and natural process (biochemistry), it helps us to manufacture new medications, and true chemistry research will always follow the scientific method.
Answer:
D. Its temperature will remain 100 C until all the vapours condenses
Explanation:
Heat absorbed by a substance to change the state of matter is known as latent heat. This heat is utilized to break the bonds between atoms of the substance so that they can undergo phase change.
So, when water boils at 100 degree Celsius then temperature will remain constant unless and until all the water changes into vapor. As it is the latent heat that breaks the bonds between hydrogen and oxygen atoms of water so that liquid state can change into gaseous state.
Since latent heat is a hidden heat, that is why, it does not get reflected and there is no change in temperature due to it.
Thus, we can conclude that it is true that temperature will remain at 100°C until all the vapor condenses for a sample of water vapor at 101°C as it cools.
