I believe this a PV = nRT question whereas
you re write the formula and solve for volume
V = nRT/ P
then you input the values
P= pressure constant
V= x
n = moles = 0.2540
R = gas constant should be 8.314J mol
T = C degrees + 273.15 = K
solve for voume
make sure all units match
and use sig figs!!!!
Altitude is height above sea level. The density of air decreases with height. There are two reasons, at higher altitudes there is less air pushing down from above,and gravity is weaker farther from earths center.
<span>The answer to question 2 is C. A magnifying glass is an example of a plano-convex lens, where one side of the lens is flat and the other is a convex curve. The answer to question 3 is either B or C. A converging lens is curved on both sides and so the rays of light coming out of it converge at a point, which is known as the focal point. When the object is inside the focal point, the image is real and inverted. If it is inside the focal point, the image is virtual and upright. Therefore the image in this question will be upright. The focal length is the distance between the image that is being magnified and the centre of the magnifying lens. A real image can only be formed when the object is further away from the lens than the focal length. Therefore, in this question, the image is virtual, as the object is closer to the lens than the focal length. The answer to question 4 is D because the index of refraction cannot be less than 1. The answer to question 5 is D because only concave mirrors can produce real images; other types produce virtual images. For question 6, the answer is D. In the rainbow, each of the colours refracts at a slightly different angle; red has the smallest refractive index and violet the largest. Of the options, orange is closest to red. For question 12, A is the answer. A higher operating temperature is not a reason fluorescent lamps are better than incandescent lamps because they have a lower operating temperature. Question 15: all of these are characteristics of different electromagetic waves. For question 18, B is true - special care must be taken when low illuminance is required to reduce glare. The answer to question 19 is B - a compound microscope makes use of two lenses. For question 20, the answer is 5 meters away. The illuminance (E) is equal to light intensity (I) divided by the square distance from the light source (d). Therefore, 4 = 100/d squared. To switch this around, d squared is equal to 100/4 = 25. Then find the square root of 25, which is 5.</span>
Answer:
-3.82ºC is the freezing point of solution
Explanation:
We work with the Freezing point depression to solve the problem
ΔT = m . Kf . i
ΔT = Freezing point of pure solvent - freezing point of solution
Let's find out m, molality (moles of solute in 1kg of solvent)
15 g / 58.45 g/mol = 0.257 moles of NaCl
NaCl(s) → Na⁺ (aq) + Cl⁻(aq)
i = 2 (Van't Hoff factor, numbers of ions dissolved)
m = mol /kg → 0.257 mol / 0.250kg = 1.03 m
Kf = Cryoscopic constant → 1.86 ºC/m (pure, for water)
0ºC - Tºf = 1.03m . 1.86ºC/m . 2
Tºf = -3.82ºC
Answer:
Explanation:
First of all, we need to understand what gravity is. Gravity in its simplest form can be best visualized as a force of attraction, that pulls all objects that have a mass towards itself.
It is usually exerted by an object with a larger mass and felt by objects with smaller masses.
Putting this into context, the earth exerts a gravitational pull on all substances with masses, which are around it. This includes the oceans, birds, airplanes, clouds, and even gasses in the atmosphere. The atmospheric gasses may be light enough to float, but they can't go very far, since gravity is constantly tugging at them. This keeps the gasses that make up our atmosphere, within a reasonable radius, which is very close to the earth. In a nutshell, gravity prevents them from floating away into outer space.