The energy of an electron can be change only by set amounts.
The electrons in an energy level of an atom can only move to a higher or lower energy level only if it absorbs or emits a certain amount of energy. If the electron does not have enough energy to move to the next energy level then it will never move.
Answer:
<em>Sand is a granular material composed of finely divided rock and mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt.</em>
Answer: density =3.377g/cm³
Explanation:
Density =( molecular weight × effective number of atoms per unit cell) / (volume of unit cell × avogadro constant)
D= (M ×n) /(V×A)
M= 137g/mol
n= 2 (For BCC)
V=a³ , where a= 4r/√3
a= (4×222)/√3
a=512.69pm
a= 512.69×10^-10cm
V= ( 512.69×10^-10)^3
V= 1.3476×10^-22cm³
D= (137×2)/(1.3476×10^-22 × 6.02^23)
D= 3.377g/cm³
Therefore the density of barium is 3.377g/cm³
1 W is equivalent to 1 J/s
So,
0.5 Wh = 0.5 (J/s) (h)
Converting h to s,
0.5 (J/s) (h) (60min/1h) (60s/1min) = 1800J
Thefore,
0.5Wh is 1800J or 1.8kJ of heat energy
if the product has lesser energy than the reactants it means enthalpy change value is positive.so it is endothermic reaction where the heat is absorbed.so kcl will formation will have positive enthalpy change .
