(a) The mass of an object remains the same always. It is independent of its location. In this case, an iron nail is ground into powder. It means that its mass will remain unchanged. Hence, (a) is the correct option.
(b) Whenever there is a change of color of an object, a chemical reaction occurs. It shows that a reaction happens there. In this problem, a paper turns yellow-brown upon exposure to sunlight. A chemical reaction takes place there. Hence, (b) is the correct option.
You have to use the equation F=ma and solve for m to get m=F/a. m=mass in kg F=force (in this case 350N) a=acceleration (in this case 10m/s²) when you plug everything in you should find that m=35kg
Ionization energy, also called ionization potential, in chemistry, the amount of energy required to remove an electron from an isolated atom or molecule
