In a closed system, energy in form of heat (work) can be exchanged but not matter.
The answer to your question is C.
Hope it helped!
Since there is no friction between the ladder and the wall, there can be no vertical force component. That's the tricky part ;)
So to find the weight, divide the 100N <em>normal</em> force by earths gravitational acceleration, 9.8m/s^2

Then;
Draw an arrow at the base of the ladder pointing towards the wall with a value of 30N, to show the frictional force.
Heat required to change the phase of ice is given by
Q = m* L
here
m = mass of ice
L = latent heat of fusion
now we have
m = 45 kg
L = 334 KJ/kg
now by using above formula


In KJ we can convert this as

so the correct answer is D option
Heptane is always composed of 84.0% carbon and 16.0% hydrogen. This illustrates the "law of definite proportions".
Answer: Option C
<u>Explanation:</u>
Proust's law states that every chemical compound used to made up of element constituents with constant proportions in terms of its mass and also independent from its sources and synthesis method. In 1779, Joseph Proust gave other names to the Proust's law as, the law of composition or definite proportions or constant compositions.
This can understood from given example like: Oxygen is composed of 8/9 of the mass of any sample of pure water while the hydrogen fills up the remaining 1/9 of the mass. The basis of stoichiometry is structured with the law of multiple proportions along the law of definite proportions.