Yes. As long as the ratio of solute and solvent is same for both solution, the solution has the same concentration. for example, solution A has 2 ml of water, and 1 ml of sucrose. Solution B has 4ml of water and 2ml of sucrose. Both has a ratio of water to sucrose by 2 : 1. they have the same concentration of 50% sucrose.
A straight line on a distance va time graph represents constant speed
I think your answer is 2 because the temperature will rise so the particles will move faster
Answer : The change in internal energy is, 900 Joules.
Solution : Given,
Heat given to the system = +1400 J
Work done by the system = -500 J
Change in internal energy is equal to the sum of heat energy and work done.
Formula used :

where,
= change in internal energy
q = heat energy
w = work done
As per question, heat is added to the system that means, q is positive and work done by the system that means, w is negative.
Now put all the given values in the above formula, we get

Therefore, the change in internal energy is 900 J.
The change in internal energy depends on the heat energy and work done. As we will change in the heat energy and work done, then changes will occur in the internal energy. Hence, the energy is conserved.
Structural isomers, as the structure of the molecule is different