This was because the experiment showed that a substance could emit radiation even while it was not exposed to light.
In a perfect world without air resistance, the top of the swing would have the most potential energy, but the least amount of kinetic energy. As the pendulum falls down, it gains more kinetic energy as it travels faster due to gravitational acceleration but loses more potential energy as it loses height. The total amount of energy in the system (the sum of kinetic and potential energy) stays the same.
B. Endorphins are released during exercise
Answer:
These properties are basically the inverse of each other.
Explanation:
- Electronegativity is the tendency of an atom to attract an electron and make it a part of its orbital.
Ionization enthalpy, is the energy required to remove an electron from an atom.
- More electronegative atoms have high ionization enthalpies If the energy required to remove an electron is less, i.e. the atom has more tendency to give electron, it would thus have less tendency to take electron.
- Values and tendency of electronegativity in the periodic table: In general, the electronegativity of a non‐metal is larger than that of metal. For the elements of one period the electronegativities increase from left to right across the periodic table. For the elements of one main group the electronegativities decrease from top to bottom across the periodic table. To the subgroup elements, there’s no regular rule.
- Values and tendency of ionization potential in the periodic table: The first ionization energy is the energy which is required when a gaseous atom/ion loses an electron to form a gaseous +1 valence ion. The energy which is required for a gaseous +1 valence ion to loose an electron to form a gaseous +2 valence ion, is called the second ionization energy of an element. In general, the second ionization energy is higher than the first ionization energy of an element.
The first ionization energies of the elements of one period increase from the left to the right across the periodic table. According to the elements of main group, the first ionization energies generally decreases from top to bottom across the periodic table.
Answer: a. 
Explanation:
When silver nitrate 
combines with potassium chromate 
,they undergo double displacement reaction in which exchange of ions take place.
The products formed are silver chromate 
which is insoluble in water and thus formed as precipitate and potassium nitrate 
is soluble in water.
