She can put chalk in vinegar as the vinegar will disintegrate the chalk chemically demonstrating chemical changes. But for physical changes she can break the chalk into small pieces by smashing it with something or her hand.
        
                    
             
        
        
        
Answer:
When the Sun emits more amount of energy than normal, "Solar flares and sunspots" occur, increasing temperature of Earth. Explanation: The Earth's temperature is governed by many factors. One of these factors is 'Solar flare'.
 
        
             
        
        
        
Isotopes refer to different atoms of the same element (i.e. same number of protons) that differ in the number of neutrons they have (giving them different atomic weights). Atomic weight is the sum of protons and neutrons (each contributes 1 atomic mass unit).
Carbon has 6 protons by definition. If you have a carbon-13 atom (the 13 referring to its mass), the atom has 13 - 6 = 7 neutrons. Since it's neutral, protons = electrons, so there are also 6 electrons.
Sulfur has 16 protons by definition. If you have a sulfur-32 atom, the atom has 32 - 16 = 16 neutrons. Since it's neutral, protons = electrons, so there are also 16 electrons.
        
             
        
        
        
Answer:
ΔK.E = 14 nJ
Explanation:
Solution:
- The charge that moves under the influence of an Electric Field produced between a potential difference (V) stores electric potential energy U within that is converted to kinetic energy.
- We will use conservation of energy on the system that contains the charged particle with charge q loses its electric potential energy U as it moves towards positively charged object that converts into a gain in Kinetic energy of the charged particle ΔK.E:
                                  ΔK.E = U
Where, 
                                  U = V*q
                                  ΔK.E = V*q
                                  ΔK.E = (7*10^-6)*(2*10^-3)
                                  ΔK.E = 14 nJ
- The gain in kinetic energy is 14 nJ.