Answer:
A. chocolate chips melting
Explanation:
It is a chemical change. cookies will soften and melt slightly as the cookies bake. the change is solid to liquid.
Answer:
Metals are thermal conductor.
Answer : The molecular weight of a substance is 157.3 g/mol
Explanation :
As we are given that 7 % by weight that means 7 grams of solute present in 100 grams of solution.
Mass of solute = 7 g
Mass of solution = 100 g
Mass of solvent = 100 - 7 = 93 g
Formula used :
![\Delta T_f=i\times K_f\times m\\\\T_f^o-T_f=k_f\times\frac{\text{Mass of substance(solute)}\times 1000}{\text{Molar mass of substance(solute)}\times \text{Mass of water(solvent)}}](https://tex.z-dn.net/?f=%5CDelta%20T_f%3Di%5Ctimes%20K_f%5Ctimes%20m%5C%5C%5C%5CT_f%5Eo-T_f%3Dk_f%5Ctimes%5Cfrac%7B%5Ctext%7BMass%20of%20substance%28solute%29%7D%5Ctimes%201000%7D%7B%5Ctext%7BMolar%20mass%20of%20substance%28solute%29%7D%5Ctimes%20%5Ctext%7BMass%20of%20water%28solvent%29%7D%7D)
where,
= change in freezing point
= temperature of pure water = ![0^oC](https://tex.z-dn.net/?f=0%5EoC)
= temperature of solution = ![-0.89^oC](https://tex.z-dn.net/?f=-0.89%5EoC)
= freezing point constant of water = ![1.86^oC/m](https://tex.z-dn.net/?f=1.86%5EoC%2Fm)
m = molality
Now put all the given values in this formula, we get
![(0-(-0.89))^oC=1.86^oC/m\times \frac{7g\times 1000}{\text{Molar mass of substance(solute)}\times 93g}](https://tex.z-dn.net/?f=%280-%28-0.89%29%29%5EoC%3D1.86%5EoC%2Fm%5Ctimes%20%5Cfrac%7B7g%5Ctimes%201000%7D%7B%5Ctext%7BMolar%20mass%20of%20substance%28solute%29%7D%5Ctimes%2093g%7D)
![\text{Molar mass of substance(solute)}=157.3g/mol](https://tex.z-dn.net/?f=%5Ctext%7BMolar%20mass%20of%20substance%28solute%29%7D%3D157.3g%2Fmol)
Therefore, the molecular weight of a substance is 157.3 g/mol
Answer: b) Crash 2; the force on the cart was stronger in this crash, so the force on the skateboard was also stronger.
Explanation: